Westlake Chemical Corporation

2007 Citi Basic Materials Symposium

December 4th, 2007

2

Safe Harbor Language

This presentation may include forward-looking statements, as defined in the Private Securities Litigation Reform Act of 1995, reflecting management’s current analysis and expectations, based on reasonable assumptions. Results could differ materially depending on such factors as business climate, business performance, economic and competitive uncertainties, ability to execute work process redesign and reduce costs, failure to complete transactions or to achieve benefit from transactions, higher manufacturing costs, change in strategies, reduced level of customer orders, risks in developing new products and technologies, adverse legal and regulatory developments including increases in the number or financial exposures of claims, lawsuits, settlements or judgments, or the inability to eliminate or reduce such financial exposures by collecting indemnity payments from insurers, environmental and safety regulations and clean-up costs, foreign exchange rates, and adverse changes in economic and political climates around the world. Accordingly, there can be no assurance that the Company will meet future results, performance or achievements expressed or implied by such forward-looking statements. As appropriate, additional factors are contained in reports filed with the Securities and Exchange Commission. This paragraph is included to provide safe harbor for forward-looking statements, which are generally not required to be publicly revised as circumstances change.

Investor Relations Contact

Steven BenderVice President, Chief Financial Office & Treasurer

Westlake Chemical Corporation2801 Post Oak Boulevard, Suite 600

Houston, Texas 77056713-960-9111

www.westlake.com

3

$2.9 Billion Integrated Materials Company

Sales $ 2,866 million

EBITDA (1)(2) $ 269 million

Net Income $ 110 million

MISSION profitable growth in businesses we understand globally in areas we can gain an edge in a disciplined and opportunistic

manner

Westlake Chemical Corporation

(LTM 3rd Qtr 2007)

(1) Adjusted EBITDA(2) Non-GAAP financial measure

Olefins Vinyls

$1,890 million

Sales $976 million

66% % of Total

34%

4

0

2,000

4,000

6,000

8,000

10,000

12,000

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

$0

$500

$1,000

$1,500

$2,000

$2,500

$3,000

$3,500

Capacity (mm lbs)

Revenues

VinylsOlefinsRevenue: 1987—2006 CAGR = 21% Capacity: 1987—2006 CAGR = 15%

Revenue ($ mm)

20 Years of Focused Organic and Acquisition-Led Growth

Growth

5

Near-Term Capacity Trends Remain Favorable

-905

4,191

683

5,258

428

1,726

5954961,211

2657

-1,359

5,214

3,831

5,739

6,731

2,954

1,376

4,162

2,835

(2,000)

0

2,000

4,000

6,000

8,000

1991 1993 1995 1997 1999 2001 2003 2005 2007 2009

Incremental Capacity

Source: CMAI (North America)

Olefin Supply Fundamentals: No major new capacity additions in olefins in North America Multiple delays in Asia/Middle East startups

Vinyls Supply Fundamentals: 4 polyvinyl chloride additions under construction in North America

Product integration levels remain very important

Energy price volatility and economic uncertainty have led to under-investment in North America

PVCPolyethyleneEthylene

Negligible net capacity additions this decade compared to prior one

1,367

Capacity (mm lbs)

6

Competitive Advantage Translates into Superior Margin

0.0%

4.0%

8.0%

12.0%

16.0%

20.0%

24.0%

2003 2004 2005 2006 LTM Q3 2007

Westlake Peer

Adjusted EBITDA Margin (1)

(1) Adjusted EBITDA is EBITDA adjusted for restructuring charges Peers include: DOW, GGC, LYO, NCX

Westlake 15.7%

Industry 9.9%

WestlakeAdvantage

> 5.0%

’03 – ’06 Average EBITDA Margin

7

Competitive Advantage: OlefinsIntegration

Merchant, 10%

Polyethylene, 53%1.5 billion lbs

Ethylene2.85 billion lbs

Styrene, 5%0.5 billion lbs

VCM, 32%1.9 billion lbs

Polyethylene, 70%2.5 billion lbs

Ethylene Styrene, 4%2.95 billion lbs 0.5 billion lbs

VCM, 26%1.9 billion lbs

PurchasedEthylene, 17%

Mid-2006: Long Ethylene Current: Full Utilization of Ethylene

Opportunity to run ethylene at even higher operating rates

Opportunity to debottleneck and curtail ethylene purchase

Enhanced margin stability; higher profits

8

Competitive Advantage: OlefinsHigher Operating Rates

Ethylene Operating Rates(1) Westlake Advantage over Peers

Higher operating rates, particularly in trough years

Operating culture; execution; integration; asset age

70

80

90

100

2000 2001 2002 2003 2004 2005 2006

%, o

pera

ting

rat

e

Industry Westlake∆ Operating

Rates

8-year, avg.

(1999 – 2006) 2.2%

Trough Years, avg. (2001- 2003)

4.3%

Source: CMAI and Westlake(1) Includes the impact of Hurricane Katrina and Rita in 2005

9

Competitive Advantage: OlefinsFavorable Scale, Age vs. Peers

North American Ethylene Plants - Site Age and Capacity

0

5

10

15

20

25

30

35

40

45

50

100 1,000 10,000

Ave

rage

Age

(yr

s)

Capacity (mm lbs)

Westlake LC

2000

Small but New

Small and Old

Large and New - Desired!

Large but Old

(Most N. Amer. Crackers)

Source: CMAI

10

Competitive Advantage: OlefinsLake Charles Feedstock Flexibility

0

20

40

60

80

J an-99 J an-00 J an-01 J an-02 J an-03 J an-04 J an-05 J an-06 J an-07 J an-08

c/lb

of Et

hylen

e

Butane Ethane Naphtha Propane Ethylene NT Price

No one feedstock is preferred all the time (18+ year history)

CMAI

Forecast

History

Source: CMAI

11

Competitive Advantage: OlefinsLake Charles Feedstock Flexibility (cont.)

’04-06 Gas Flexible Lake Charles Feedslate (%

volume)

Liquid-flexible Lake Charles Feedslate

Capability (% volume)

2007 Q3 YTD U.S. Feedslate (% volume)

Project completed in May 2007

Full potential by mid – ’08

Feed-Flex improves cycle average margins and reduces earnings volatility

Benefits include Energy cost reduction

100 MM lbs capacity increase

Reduced earnings volatility

Butane1%Propane

14%

Ethane85%

Light Naphtha

21%

Propane5%

Ethane74%

Light Naphtha

25%

Propane22%

Butane5%

Gas oil6%

Ethane42%

Source: Jabcobs Consultancy

12

Competitive Advantage: OlefinsFavorable PE Product Mix

3.4

2.1

0

1

2

3

4

cen

ts/ l

bs

LDPE Has Been More Profitable On Average Than Other PE

Grades

Dow Chemical (DOW), Lyondell Chemical (LYO), Westlake Chemical (WLK),Exxon/Mobil (XOM), PEMEXSource: CMAI

LDPE Capacity Post-Eastman

LDPE v. LLDPE LDPE v. HDPE

‘97 - ‘06‘97 - ‘06

1,576 1,5561,500

1,468

860

0

600

1,200

1,800

DOW LYO WLK XOM PEMEX

billi

on lb

s

Befo

reC

om

bin

ed

¢

¢

13

Competitive Advantage: OlefinsFavorable PE Product Mix (cont.)

Westlake’s PE Business Is Favorably Weighted to LDPE

0% 20% 40% 60% 80% 100%

Among the highest LDPE product mix percentage in U.S. and Canada

Westlake

Koch Industries

Lyondell

Dow

ExxonMobil

ChevronPhillips

NOVA

Ato Fina

Ineos

Formosa

Source: Chemical Data, Inc.

14

Competitive Advantage: OlefinsIncreased PE Capacity Through the Eastman Acquisition

LLDPE, 29%

LDPE, 26%

HDPE, 45%

Total Capacity: 146 billion poundsSource: CMAI

Pre-Eastman Acquisition

2006

Post-Eastman Acquisition

2007

Eastman acquisition expands into the most profitable PE product category

Upgrades and broadens our PE mix

Westlake is benefiting from the full accretive effects of the Longview PE assets after a smooth transition earlier in the year

Global End Use Demand(% share)

Westlake Capacity(% share)

LDPE, 61%

LLDPE, 30%

HDPE, 9%

LLDPE, 33%

LDPE, 62%

HDPE, 5%

66 billion

38 billion

42 billion

Total Capacity: 1.4 billion pounds Total Capacity: 2.5 billion pounds

66 billion

15

Competitive Advantage: OlefinsTRINIDAD Project Update

Globally competitive ethane-based ethylene, polyethylene facility

Ethylene and polyethylene capacities should approximate 1.25 billion lb/yr

Estimated capital cost: $1.9 billion

Bolsters profitable growth and lowers earnings volatility

Markets: The Americas

Ownership: Westlake (majority shareholder); Trinidad & Tobago

$0.00 $5.00 $10.00

UK

USA

Canada

China

India

Qatar

Trinidad

Russia

Iran

Oman

Saudi Arabia

Source: American Chemical Council

Scope/StatusNatural Gas around the World,

2006(US$ per million BTUs)

16

Olefins: Managing the Cycle

Raw material diversification and energy conservation

Feed-Flex improves cycle average margins and reduces earnings volatility

Capital investments in multiple energy saving projects and ethylene capacity debottlenecks

Product mix, ethylene integration Greater mix of LDPE which exhibits higher

margins versus other grades of PE

Longview acquisition is accretive, adds PE capacity, brings specialty acrylate copolymers and Epolene® polymers, and improves ethylene integration

17

Olefins: Managing the Cycle (cont.)

Improved ethylene balance Maintain high operating rates during trough

periods

Planned investment in Trinidad Globally competitive PE complex with start up for

2011

Marketing PE in The Americas

Middle East capacity expansions delayed

18

Competitive Advantage: Vinyls Further Improving Our Integration

Polyvinyl Chloride

(PVC)

Caustic Soda

Fabricated

Products

PVC

VCM

PVC Fabricate

d Products

Vinyl Chloride Monomer

(VCM)

Ethylene Dichloride (EDC)

CausticSoda

Chlorine

Ethylene

Vinyls Segment

Purchased

Chlorine

Merchant Sales

Chlor-Alkali

19

Competitive Advantage: VinylsHigher Operating Rates

70

80

90

100

2000 2001 2002 2003 2004 2005 2006

%, of

opera

ting r

ate

Industry Westlake

Higher WLK operating rates, particularly in trough years

Operating culture, execution, integration

Westlake Advantage over Peers

∆ Operating Rates

8-year, avg.(1999 – 2006)

6.0%

Trough Years, avg.(2001- 2003)

9.0%

Vinyls Operating Rates

Source: CMAI and Westlake

20

Competitive Advantage: VinylsStrong Down-Stream PVC Integration

PVC Pipe

Residential and Ranch Fence

Windows

PVC Pipe #1 or #2 in areas served 800 mm lbs of annual capacity Westlake focuses on large

diameter pipe which has strong growth rates

Westlake capacity is 20% residential

PVC pipe is protected from imports due to transportation barriers

Fence, Deck and Railing # 2 producer in North America 75mm lbs. of annual capacity Projected industry growth of

10.3% through 2010(1)

Doors and Window Profiles 30mm lbs. of annual capacity Projected industry growth of 6.5%

through 2010(2)

Source: The Freedonia Group, Inc. (1) US Plastic & Composite Fence Demand, Industry Study – Fence, November, 2006 (2) US Plastic Window & Door Demand, Industry Study – Windows & Doors, January, 2007

21

Competitive Advantage: VINYLSLeadership in Regions we Chose to Serve

North American Pipe Corporation

Locations(> 80% of PVC fabricated products volume)

Vinyl Pipe Plant LocationsCalvert City, KY

Geismar, LA

22

Competitive Advantage: VinylsFavorable Demand Drivers

    2005 Grade

Trend

Roads D              

Bridges C                

Transit D+              

Aviation D+                

Schools D                

Drinking Water

D-              

     2005 Grade Trend

Wastewater D-              

Dams D              

Solid Waste C+                

HazardousWaste

D                

NavigableWaterways

D-              

Energy D              

The strong long-term growth outlook for large diameter plastic pipe reflects the need to expand and modernize an aging pipe infrastructure

Source: 2005 Report Card for America’s Infrastructure, American Society of Civil Engineers

23

Competitive Advantage: VinylsFavorable Demand Drivers

0

50

100

150

200

250

300

350

400

2002 2003 2004 2005 2006 2007 2008$

in b

illio

n

Lodging Office Commercial Highway Water & Sewer

Non-residential construction spending

Source: Actual: U.S. Census Bureau, Forecasts: Reed Construction Data

Other, 16%

Profiles &

Tubes, 25%

Film &

Sheet, 8%

Bottles, 1%Wire &

Cable, 4%

Pipe &

Fittings,

46%

(1) Excludes consumption related to exports

2006 PVC Demand by End Consumption(1)

0 5,000 10,000 15,000 20,000

2006

1980

(mm lbs)

Rigid Flex

55% 45%

74% 26%

Source: CMAI 2007 World Vinyls Analysis

North American PVC Demand (mm lbs)

24

Competitive Advantage: VinylsChina Footprint

Established 1992, J.V. with Westlake and Norsk Hydro. Westlake has approximately a 60% share in the Joint Venture

Located in Suzhou, Jiangsu Province, China - Operations include:

140 KTA PVC resin plant 60 KTA Calendering facility

Suzhou Huasu Plastics Company markets PVC resin and film products to both domestic and export markets

25

Vinyls: Managing the Cycle

High degree of vertical integration Chlor-Alkali options (under evaluation) will provide integration

and earnings power to the Vinyls segment

Integration across the chain translates into higher operating rates

Forward integration into fabricated products

Focus on large diameter PVC pipe: higher growth rate, less exposure to housing

Opportunities for debottlenecks

Financial Overview

27

Superior Performance versus Peers

(1) Adjusted EBITDA is EBITDA adjusted for restructuring charges(2) Return on capital employed (ROCE) is defined as operating income (adjusted for restructuring charges) divided by average

capital employed.Peers include: DOW,GGC, LYO, NCX

Return on Capital Employed

(ROCE)(2)

Range from FY 2003 to LTM 2007

0%

10%

20%

30%

40%

WLK Peers Avg

28.9%

5.8%

15.9%

4.4%

28.9%

5.8%

15.9%

4.4%

0.0%

4.0%

8.0%

12.0%

16.0%

20.0%

24.0%

2003 2004 2005 2006 LTM Q3 2007

Westlake Peer

Adjusted EBITDA Margin (1)

28

Superior Balance Sheet

0.6x1.0x

1.3x

2.3x

7.6x

0.0x

2.0x

4.0x

6.0x

8.0x

10.0x

WLK DOW NCX LYO GGC

Debt to Capitalization 21%Net Debt To Capitalization 12%

September 30, 2007

Cash & cash equivalents

$139.3

Long-term debt, incl. current portion

6.625% senior notes due 2016

250.0

Other debt 85.9

Total debt 335.9

Stockholders’ equity 1,267.5

Total capitalizationS1,603.

4

Actual Capitalization ($ millions) Net Debt / EBITDA – LTM 9/30/2007

29

Disciplined Investment History

$0

$50

$100

$150

$200

$250

$300

$350

$400

$450

'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07E

0%

10%

20%

30%

40%

50%

A cquis it ion s

D iscr et ion ar y

M ain t en an ce

$121

$262

$307

$79

$77

$44

$86

$86

$45

$216

$29

$391

’95~’06 Average % of Sales % of Depreciation

Maintenance 2.7% 50.8%

Discretionary 5.6% 103.0%

Subtotal 8.3% 153.8%

Total CAPEX as % of Sales

CA

PEX

($

mill

ion) C

APEX

as %

of S

ale

s

$130

30

Managing the CyclesExtended Improved EBITDA in next Industry Trough

Volume growth and improved integration Chlor-Alkali: Expansion (80,000 tons) in 2002 Acquired Geismar facility (600 mm lbs, PVC and 600 mm

lbs VCM) in 2002 Acquired Bristolpipe (300 mm lbs, PVC) in 2004 Acquired Eastman PE business (1.1 billion lbs, PE) in 2006 Petro 2 feedstock flexibility project (100 mm lbs, ethylene) Chlor-Alkali, PVC resin and large diameter PVC pipe expansion – 2008/2009

Energy reduction, asset enhancement Petro 1 energy cost reduction and yield improvement Petro 2 feedstock flexibility project Chlor-Alkali conversion from mercury to membrane

technology

31

Westlake Valuation

Enterprise Value to Adjusted LTM EBITDAUpdated: November 27, 2007

Westlake is trading among the lowest enterprise multiples compared to peers

9.89.2

8.4 8.3 8.28.0 7.8

7.5 7.57.2

6.9

6.1 6.05.4

0.0

2.0

4.0

6.0

8.0

10.0

HUN POL FMC GGC OLN ROC CE CBT FOE DOW LYO NCX CEM WLK

32

Investment Conclusions

Focused best-in-class plastics producer Out-performing peers Strengthen operating base

Multiple sources of competitive advantages Integration and location of assets Operating philosophy with matching track record

Westlake specific initiatives: an ongoing feature Acquisitions, debottlenecks, advantaged “greenfield”

plants Track record of investing prudently Strong financial discipline

Management team committed to creating value and financial flexibility to fund our growth strategy

Appendix

34

Appendix

LTM

2003 2004 2005 2006 Q3 2007

Adjusted EBITDA 160,728 326,878 450,932 411,183 268,938

Debt Retirement Cost (11,343) (15,791) (646) (25,853) -

EBITDA 149,385 311,087 450,286 385,330 268,938

Less:

Income Tax (provision) benefit (8,747) (69,940) (118,511) (87,990) (40,982)

Interest expense (38,589) (39,350) (23,717) (16,519) (15,943)

Depreciation & Amortization (87,293) (81,075) (81,241) (86,262) (101,713)

Net Income 14,756 120,722 226,817 194,559 110,300

Changes in operating assets and liabilities 56,219 (35,129) 45,885 28,773 (12,215)

Deferred income taxes 7,112 65,188 45,745 13,852 20,232

Cash flow from operating activities 78,087 150,781 318,447 237,184 118,317

Reconciliation of EBITDA to Net Income (Loss) and to Cash Flow from Operating Activities –

(in $ Thousands)