John Moffat, the founder of this firm, was born in Goshen, New York in 1788. He spent time in the gold fields of Georgia and North Carolina as a young man. Moffat then established himself as a well-known assayer in New York.

In the summer of 1849, he arrived in San Francisco along with his partners Curtis, Perry and Ward. Moffat & Company started out as a smelting and assaying business. The firm received many endorsements from prominent bullion dealers, business leaders and even the U.S. Secretary of the Treasury.

At first, they issued only gold ingots. $5.00 and $10.00 gold coins dated 1849 and 1850 were struck under the aegis of Moffat & Co. exhibiting a similarity to circulating U.S. coins of the same denomination.

From September 1850 until December 1853, Moffat & Co. operated in a semi-official capacity as the U.S. Assay Office. In 1851, under the direction of Augustus Humbert, the minting of gold coins began at this new U.S. Assay Office. Moffat left his company on December 24, 1851 in order to pursue river mining opportunities.

Moffat & Company enjoyed the finest reputation of all the California private mints. The two surviving members of the firm, Curtis and Perry, transferred operations to the U.S. Mint at San Francisco in 1854.