These Houston-based companies operate predominantly in chemical manufacturing, oil and gas, and wholesale building materials. The list includes large firms such as LyondellBasell, a global chemical company producing polymers and polyolefins, and Westlake, which manufactures petrochemicals and building products. Other notable companies are CITGO, operating in refining and marketing petroleum products, and HALLIBURTON ENERGY SERVICES, a long-standing provider to the global energy industry.
A significant number of these companies are well-established, with several founded in the mid-20th century, such as TPC Group (1944) and Kuraray America, Inc. (1963). However, there is also a presence of more recently established firms like LyondellBasell (2007) and Vibrantz Technologies Inc. (2022), indicating a mix of mature and newer entities in the Houston industrial landscape.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
LyondellBaselllyondellbasell.com
Leading global chemical company producing innovative polymers and polyolefins for sustainable transportation, food safety, clean water, and healthcare applications. |
15,172 | |||
| 2 |
Westlakewestlake.com
Manufacturing and supplying petrochemicals, plastics, and building products globally, enhancing daily life through quality products and services. |
6,574 | |||
| 3 | 5,326 | ||||
| 4 |
M-I SWACO US Landslb.com
An innovative company offering customized drilling fluid solutions through cutting-edge technology and a strong supply chain, focusing on client satisfaction and cost reduction |
3,109 | |||
| 5 |
Motiva Enterprises LLCmotiva.com
A Houston-based company refines, distributes, and markets petroleum products in the Americas with a large manufacturing complex in Texas Owned by Aramco |
2,803 | |||
| 6 |
Ascend Performance Materialsascendmaterials.com
Global manufacturer specializing in nylon 6,6 materials for diverse applications including apparel, automotive parts, electronics, and industrial products. |
2,065 | |||
| 7 |
Vibrantz Technologies Inc.vibrantz.com
A global technology leader specialized in color solutions, functional coatings, and specialty minerals to enhance products across various end markets |
1,632 | |||
| 8 |
HALLIBURTON ENERGY SERVICEShalliburton.com
Global energy industry provider with over a century of experience in maximizing reservoir value through various products and services worldwide |
1,626 | |||
| 9 |
Cemex UScemexusa.com
Global leader in supplying cement, aggregates, concrete, and urbanization solutions while driving innovation to solve building challenges and promote sustainable living |
1,476 | |||
| 10 |
Quanexquanex.com
A global manufacturing company focused on innovation, efficiency, community impact, shareholder value, and employee development in various markets worldwide |
1,420 | |||
| 11 |
Lummus Technologylummustechnology.com
A global leader in developing technology solutions for a sustainable, low carbon future, specializing in process technologies, catalysts, equipment, and digitalization |
1,027 | |||
| 12 |
Axiall, a Westlake Companywestlake.com
Chemical and building products company acquired by Westlake Corporation, focusing on manufacturing and supplying essential industrial materials. |
849 | |||
| 13 |
A. Schulman, Inc.lyondellbasell.com
production of plastics, chemicals, and refining products used in packaging, water pipes, automotive, electronics, and appliance industries worldwide. |
840 | |||
| 14 |
TPC Grouptpcgrp.com
A Houston-based company specializing in chemical products for major chemical and petroleum companies worldwide, focusing on hydrocarbon processing and specialty chemicals |
781 | |||
| 15 |
Kuraray America, Inc.kuraray.us.com
pioneers, manufactures, sells resins, chemicals, activated carbon, fibers, textiles, specialty dental materials, other functional products, improving environment, enhancing global life quality of life |
757 | |||
Want more companies than this list?This page shows the largest ones only. Connect to Tamtam to see every company that matches, filter by size, industry or growth, and reach their decision-makers. | |||||
| 16 | 749 | ||||
| 17 |
UPGupgintl.com
A US-based manufacturer specializing in OEM, contract manufacturing, and injection molding for data centers, automotive, and general industrial markets worldwide |
625 | |||
| 18 |
Genesis Energy, L.P.genesisenergy.com
A diversified midstream energy company offering supply and logistics solutions in offshore pipeline transportation, chemicals, onshore facilities, and marine transportation |
618 | |||
| 19 |
Continental Carboncontinentalcarbonasia.com
A technology leader in the carbon black industry, utilizing waste streams to produce high-quality carbon black and tail gas for renewable power generation |
596 | |||
| 20 |
Rockwater Energy Solutionsselectwater.com
Select Chemistry, formerly Rockwater, offers products and services for the water industry, focusing on unity and connectivity with customers |
531 | |||
| 21 |
Vortex Companies - Trenchless Infrastructure Rehabilitation Solutionsvortexcompanies.com
The company provides advanced trenchless technologies and turnkey services to effectively renew water, sewer, and industrial infrastructure with experienced personnel |
505 | |||
| 22 |
RectorSealrectorseal.com
A leading provider of quality solutions for HVAC/R, plumbing, electrical, and construction trades, focusing on customer service and employee satisfaction |
504 | |||
| 23 |
AES Drilling Fluidsaesfluids.com
Specializing in designing and manufacturing drilling fluids tailored to customer needs, ensuring quality and reliability from the well site to the office |
500 | |||
| 24 |
Ketjen Corporationketjen.com
Provides advanced catalyst solutions to industries like refining, petrochemicals, and specialty chemicals to improve production performance and business value globally |
488 | |||
| 25 |
Westlake Pipe & Fittingswestlakepipe.com
A leading PVC pipe manufacturer in North America, producing gasketed, solvent welded, and restrained joint pipes for various markets with superior customer service |
482 | |||
| 26 |
Ecoservicesecovyst.com
A leading provider in sulfuric acid regeneration and supply, offering liquid aluminum sulfate, industrial waste treatment, and tank cleaning services with a focus on reliability and safety |
346 | |||
| 27 |
CARBOcarbo.tech
A leading technology and service company offering innovative solutions in various industries with a focus on value and performance |
331 | |||
| 28 |
UTEX Industries Inc.utexind.com
Leader in designing and manufacturing custom high-performance sealing solutions for Oil & Gas, water distribution, aerospace, and industrial markets worldwide |
329 | |||
| 29 |
Aegis Chemical Solutionsaegischemical.com
Aegis Chemical Solutions provides high-quality chemical treatments and technical services for oilfield applications, including production chemicals, completion chemicals, and water treatment solutions |
240 | |||
| 30 |
EverZinceverzinc.com
Global provider of specialty zinc materials for various industries, with manufacturing operations worldwide and a focus on innovation and customer service |
232 | |||
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How this list is built
Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 12, 2026.
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