Chemical Abstracts Service (CAS)

Chemical Abstracts Service (CAS)

Chemical Abstracts Service (CAS)

CAS, a division of the American Chemical Society, is dedicated to the ACS vision of improving people`s lives through the transforming power of chemistry. The CAS team of highly trained scientists finds, collects, and organizes all publicly disclosed substance information, creating the world`s most valuable collection of content that is vital to innovation worldwide. Scientific researchers, patent professionals and business leaders around the world rely on a suite of research solutions from CAS that enables discovery and facilitates workflows to fuel tomorrow’s innovation.

Company details

Chemical Abstracts Service P.O. Box 3012 , Columbus , Ohio 43210 USA
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Business Type:
Professional association
Industry Type:
Fine Chemicals
Market Focus:
Globally (various continents)
Year Founded:

What is a CAS Registry Number?

A. CAS Registry Numbers (often referred to as CAS RN® or CAS Numbers) are universally used to provide a unique, unmistakable identifier for chemical substances. A CAS Registry Number itself has no inherent chemical significance but provides an unambiguous way to identify a chemical substance or molecular structure when there are many possible systematic, generic, proprietary or trivial names.

CAS Registry Numbers are used in many other public and private databases as well as chemical inventory listings and, of course, are included in all CAS-produced databases.

Tell me briefly about CAS products.

A. CAS offers online, Web-based and desktop access to databases covering science, engineering, technology, patents, business information and much more. These products are designed to accommodate a wide range of information needs, whether you are an infrequent searcher who only needs a few quick answers or a professional searcher who requires a more powerful and comprehensive set of search tools.

CAS products are fee-based and generally require you to set up an account.

Does CAS offer any free services?

A. CAS offers Common Chemistry, a free web resource that contains CAS Registry Numbers for approximately 7,900 chemicals of widespread general public interest. Common Chemistry is helpful for those who know either a name or CAS Registry Number of a common chemical and want to pair both pieces of information. CAS has collaborated with Wikipedia in developing this resource and encourages you to use the Wikipedia link (when available) or other sources of general information on chemistry, to learn more about these chemicals.

The CAS Source Index (CASSI) Search Tool is another free online resource intended to support researchers and librarians who need accurate bibliographic information. Use this free tool to quickly identify or confirm journal titles and abbreviations for publications indexed by CAS since 1907, including serial and non-serial scientific and technical publications.  Locate the bibliographic details you need quickly and easily. Search by Title, Abbreviation, CODEN, ISBN, or ISSN.

Which CAS product is right for me?

A. This depends on factors such as how comprehensive your search and answers need to be, your familiarity and experience with online searching, the medium you wish to search in and how frequently you need to search. Of course, cost is also a consideration.

If you are unsure about the most suitable product for you, the CAS Customer Center will be happy to help you.

  • SciFinder® is a research discovery tool, suitable for both professional searchers and research scientists. You do not have to be an expert searcher to use SciFinder. Many organizations around the world use SciFinder to give their scientists direct access to CAS databases. SciFinder packages and subscriptions can be tailored to smaller groups as well.
  • STN® is the access point to a comprehensive collection of databases covering science, technology, patents, engineering and business information. It is a command-based online service and at least some training in the STN search language is recommended in order to benefit from the precision and power of the system. STN Express® will help make STN searching more efficient and productive.
  • STN on the WebSM brings all the power and functionality of STN to a Web-based system. Structure searching capabilities are included.
  • STN® Easy is a Web-based interface to the most popular databases available on STN. There is no command language to learn, so this service is suited to both infrequent searchers and those who need a simpler, more guided information resource.
  • MethodsNow® features step by step instructions for analytical and synthetic methods. Users can search and compare methods side by side in easy to read table formats.
  • PatentPak® is a robust patent workflow solution designed to reduce the time needed to acquire and search through multiple patents. It is available in SciFinder and STN.
  • NCI™ Global is a web-based product for those involved with regulatory and compliance work.

Who do I contact if I have a question or problem?

A. You have several options depending on the nature of your question or concern. Use the following as a guide:

  • Contact the CAS Customer Center for general questions about CAS or STN products. This would include account setup and status, costs, ordering information, obtaining user documentation, etc. The CAS Customer Center can also assist with search strategies and using CAS products. The Center is open 8 a.m.- 6 p.m. Eastern Time (Monday-Friday).
  • Contact FIZ AutoDoc when you need to order a copy of a journal article or patent.
  • Contact CAS Client Services if you need confirmation/assignment of CAS Registry Numbers and chemical names or substance identification.
  • For inquiries outside North America, see the list of official CAS/STN representatives who can answer CAS- and STN-related questions.
  • We also recommend trying the site search feature of this website. It doesn't search the fee-based databases for references, CAS Registry Numbers, etc., but it is a useful way to find content on the website.