British philanthropist, historian, bibliophile, and patron of learning who subsidized the publication of a number of major works of Jewish literature.

From 1857 to 1874, Mocatta directed the firm (founded by his grandfather) of Mocatta and Goldsmid, bullion brokers to the Bank of England. Upon retirement he devoted his time to charitable works—supporting better housing for workers, contributing money to almost every hospital in London, and promoting education. As a Jew, he was especially concerned with the plight of the Jewish poor.

Mocatta's chief historical work is the survey The Jews of Spain and Portugal and the Inquisition (1877), which was later translated into several languages. Mocatta is perhaps best remembered as a patron of learning and as a bibliophile. He subsidized the publication of such major works as Zur Geschichte und Literatur (1845; “On History and Literature”) by Leopold Zunz and the classic History of the Jews (1891–92), a condensed and updated translation of Heinrich Graetz's Geschichte der Juden von den ältesten Zeiten bis auf die Gegenwart, 11 vol. (1853–76). Mocatta bequeathed his fine library of Jewish history and English Judaica to the University College of London. The Mocatta Library is administered jointly with the Jewish Historical Society of England, of which Mocatta was president from 1900 to 1902.