ACS Style Guide - Websites

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ACS Website Citation Format

ACS website citations require an access date because online content can change or disappear. The URL is included in full, and the access date follows in parentheses using ISO date format. For chemistry research, common online sources include PubChem, NIST databases, and journal publisher websites.

Basic Format:

Author, A. B. Title of Page. Site Name. URL (accessed YYYY-MM-DD).

No Author Format:

Title of Page. Organization Name. URL (accessed YYYY-MM-DD).

URL Formatting:

Include full URL with https://

Access Date:

ISO format in parentheses: (accessed 2026-03-21)

ACS Website Citation Examples

Website with Author

Smith, A. B. Chemical Safety Guidelines. American Chemical Society. https://www.acs.org/safety (accessed 2026-03-21).

In-text: Superscript number (e.g., ¹)

Website without Author

Periodic Table of Elements. Royal Society of Chemistry. https://www.rsc.org/periodic-table (accessed 2026-03-21).

In-text: Superscript number (e.g., ²)

Government Website

U.S. Environmental Protection Agency. Toxics Release Inventory. https://www.epa.gov/toxics-release-inventory (accessed 2026-03-21).

In-text: Superscript number (e.g., ³)

Online Database Entry

PubChem. Compound Summary for CID 2244, Aspirin. https://pubchem.ncbi.nlm.nih.gov/compound/2244 (accessed 2026-03-21).

In-text: Superscript number (e.g., ⁴)

Common Chemistry Online Sources

Databases

PubChem (compound data)
NIST Chemistry WebBook
SciFinder / CAS registry
ChemSpider

Institutional Sources

American Chemical Society (acs.org)
Royal Society of Chemistry (rsc.org)
EPA chemical databases
IUPAC nomenclature resources

Frequently Asked Questions

How do I cite a website in ACS format?

Include the author (if available), title of the page, website or organization name, URL, and access date in parentheses. Example: Smith, A. B. Chemical Safety Guidelines. American Chemical Society. https://www.acs.org/safety (accessed 2026-03-21). The access date is essential for online sources.

What if there is no author on a website in ACS?

Start with the title of the page or the organization name. Example: Chemical Safety Guidelines. American Chemical Society. https://www.acs.org/safety (accessed 2026-03-21). If the organization is both author and publisher, list it once.

How do I format the access date in ACS citations?

The access date is placed in parentheses at the end of the citation in the format "(accessed YYYY-MM-DD)." Example: (accessed 2026-03-21). This format uses the ISO date standard preferred by ACS.

How do I cite a government or institutional website in ACS?

Use the organization or agency as the author. Example: U.S. Environmental Protection Agency. Toxics Release Inventory. https://www.epa.gov/toxics-release-inventory (accessed 2026-03-21). Government data sources are common in chemistry research.

Should I include the full URL in ACS website citations?

Yes, include the full URL. Unlike some styles, ACS does not remove "https://" from URLs. If a DOI is available for online content, prefer the DOI over the URL.

How do I cite an online database in ACS format?

For databases like PubChem or SciFinder, include the database name, the specific entry or search details, URL, and access date. Example: PubChem. Compound Summary for CID 2244, Aspirin. https://pubchem.ncbi.nlm.nih.gov/compound/2244 (accessed 2026-03-21).

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