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Reaxys is a chemistry database and search engine published by Elsevier. It combines curated chemistry data from journals, books and patents with natural-language search and retrosynthesis tools, so chemists can look up substances, reactions and properties in one place. This guide answers the question “what is Reaxys?”, describes what it covers and how its interface is organised, and sets out where it fits next to other chemistry resources. Facts below come from Elsevier’s own Reaxys pages, checked 2026-10-28.
What Reaxys is
Elsevier describes Reaxys as “a comprehensive chemical database and chemistry search engine” that brings together chemistry data with AI-assisted search and retrosynthesis tools. Access is licensed, so it is typically reached through an institution or organisation that holds a licence.
In practice, people use it to answer questions such as: what is known about this compound, how has it been made before, under what conditions, and what properties or bioactivity have been reported. For the wider field this sits in, see what is cheminformatics.
Who runs it and what it covers
Reaxys is published by Elsevier. According to Elsevier’s product page, the content is curated from peer-reviewed journals, books, reviews and conference proceedings, and it includes major reference handbooks such as the former Beilstein and Gmelin handbooks. The main content types are:
- Substances: experimental data including spectra, physical properties and commercial availability.
- Reactions: published and AI-predicted synthesis routes, with conditions, procedures and references. A feature called Conditions Navigator ranks literature-backed reaction conditions.
- Properties and bioactivity: physicochemical, toxicological and pharmacological data, including normalised bioactivity from in vitro and in vivo studies covering toxicity and ADME.
- Patents: Elsevier states that Reaxys holds the largest collection of new pharma and chemical patents, drawn from 105 patent offices, with titles, abstracts and claims translated into English. Patents become searchable roughly five days after publication. These are Elsevier’s own claims, not independently audited figures.
Elsevier gives the overall scale as more than 1 billion chemistry data points (again, the publisher’s figure). Access to the data through an API, flat file or MCP connection is licensed separately, and a proprietary version can integrate an organisation’s in-house data.
How to search and use it
Elsevier’s Reaxys guide for users organises the interface around a small number of tools. Where you sign in depends on your institution: use the Reaxys.com link from the Elsevier product page or your library’s database list.
- Quick Search: the recommended starting point for most tasks. You can enter text in natural language or use structure, reaction, keyword and property-value searching, including structure combined with text.
- Query Builder: for refinement and advanced, multi-field queries when Quick Search is not specific enough.
- Results view: where hits are reviewed and narrowed with filters. Elsevier describes the query process as transparent, so you can see how your search was interpreted.
- Retrosynthesis: planning tools that suggest synthesis routes, drawing on published and AI-predicted reactions.
- Managing your searches: saving and revisiting searches. Elsevier’s help pages cover this in detail.
For step-by-step instructions, Elsevier’s own “How to search” and “Navigating results” pages are the authoritative reference.
Strengths and limits
Strengths
- Breadth in one interface: substances, reactions, properties, bioactivity and patents.
- Search by structure, reaction or property value as well as by keyword and natural language.
- Reaction conditions ranked by literature support through Conditions Navigator.
- Patent content with English-translated titles, abstracts and claims.
Limits
- It is a licensed product, so access depends on a licence held by your institution or company. Features can vary by licence.
- Coverage figures such as the 1 billion data points and the patent claims are Elsevier’s own statements.
- Data export, API and flat-file use are separate licence arrangements.
Alternatives and related resources
| Resource | What it is (per its publisher) | Access |
|---|---|---|
| Reaxys | Elsevier’s chemical database and search engine with literature, reaction, property and patent data | Licensed; separate licence for API or flat-file data |
| CAS SciFinder | A chemical compound database from CAS, curated by scientists and enhanced with AI-assisted tools; covers substances, reactions, literature, patents, regulatory and supplier data | Features vary by product licence |
| ChEMBL | A manually curated database of bioactive molecules with drug-like properties, combining chemical, bioactivity and genomic data; part of the ELIXIR infrastructure | Provided under a Creative Commons Attribution-ShareAlike 3.0 Unported licence |
Related reading: PubChem as a chemistry and bioassay data repository and Boolean search operators for literature searching.
Frequently asked questions
What is Reaxys?
Reaxys is Elsevier’s chemical database and chemistry search engine. It brings together curated data on substances, reactions, properties and patents with AI-assisted search and retrosynthesis tools.
Who publishes Reaxys?
Elsevier publishes Reaxys, and it hosts the product and help pages cited in this guide.
What kinds of data does Reaxys contain?
Substance data including spectra and properties, reaction data with conditions and procedures, bioactivity and toxicology data, and patent content, curated from journals, books, reviews, conference proceedings and handbooks.
Is Reaxys free?
Reaxys is a licensed product, so access is typically arranged through an institution or organisation. Elsevier’s Reaxys.com link is the place to start.
Can Reaxys predict synthesis routes?
Elsevier describes Reaxys as offering published and AI-predicted synthesis routes together with retrosynthesis tools.
Where do I find the Reaxys sign-in?
Elsevier’s Reaxys product page links to Reaxys.com, and many users reach it through their institutional library.
Sources
- Elsevier, Reaxys product page: https://www.elsevier.com/products/reaxys (checked 2026-10-28)
- Elsevier Reaxys guide: https://elsevier.libguides.com/reaxys (last updated Oct 1, 2026; checked 2026-10-28)
- Elsevier, Reaxys results and search: https://www.elsevier.com/solutions/reaxys/how-reaxys-works/results (checked 2026-10-28)
- CAS SciFinder product page: https://www.cas.org/solutions/cas-scifinder-discovery-platform/cas-scifinder (checked 2026-10-28)
- ChEMBL: https://www.ebi.ac.uk/chembl (checked 2026-10-28)
