Getting SIC Code and Description

Hi, how can I request for SIC Code and Description of a company using Company House API?

See the documentation at:

The endpoint you need will be the Company Profile one:

The data returned will have the SIC code here:

Description of a Company

I am not sure what you want or expect but the best way to investigate what is available is probably to look up some companies in the Beta website (you can do this now without any registration): https://beta.companieshouse.gov.uk/

If you want to get this information for lots (or all!) companies at once there are other data products which might be better for you - see Companies House data products - GOV.UK