James Douglas was born on November 4, 1837, in Quebec City, Quebec, the son of James Douglas (1800-1886), an eminent surgeon and manager of the Beauport Lunatic Asylum.

He was a Presbyterian minister, metallurgist, industrialist, historian, and philanthropist. He was educated at Queen's College, Kingston, Upper Canada (B.A., 1858) and the University of Edinburgh, where he was ordained as a minister in 1861. Shortly afterward, he made a surprising career change, becoming a mining chemist in Quebec. From 1871 to 1874, he served as a professor of chemistry at Morrin College, affiliated with McGill University, and in 1864, he became managing director of the Harvey Hill Copper Company in Quebec. In 1875, he entered industrial life in the US. He discovered valuable copper deposits in Arizona, invented new metallurgical processes for the reduction of copper, and reached the presidency of major mining companies, e.g., the Phelps-Dodge Corporation, the Copper Queen Consolidated Mining Company in Arizona, the Detroit Copper Company at Morenci Arizona, and the United Globe-Old Dominion mines at Globe Arizona. He wrote several books on Canadian history and heritage. He was a trustee of the American Museum of Natural History and received an honorary degree of LL.D. from McGill University. He financed many libraries, such as the library of the Literary and Historical Society of Quebec and supported the Protestant Hospital for the Insane in Montreal, the institution that took on the name of Douglas Hospital in 1965 as a tribute to James Douglas, Jr. and his father.

In 1860, he married Navine Douglas (1838–1922). He died on June 25, 1918, in Manhattan, New York.