After he had retired from the business in 1874 he devoted himself to works of public and private benevolence, especially in the deprived East End of London.

Besides this he was a patron of learning and himself an author of historical works, the chief of which was The Jews of Spain & Portugal and the Inquisition.

He bequeathed his fine library to the Jewish Historical Society of England, of which he was at one time president.

[1][2] A fountain was erected to his memory by the people of East London, outside St Botolph's Church, Aldgate.

[3] A man of letters, Mocatta had vast correspondences with the great and the good of his era.