Mr. Kempner was a native of New York, where he began his career after graduating Phi Beta Kappa from Columbia University. He was managing executive of Heidelbach Ickelheimer & Company from 1920 to 1927 and then served as a partner for varying periods until 1992 with that firm and with Stern, Kempner & Company and Spencer B. Rock & Company.
He was a lieutenant colonel in the Army's finance department in World War II, then became president and director of the Industrial Capital Corporation in San Francisco, an early venture capital company, where he remained until 1965.
Mr. Kempner was also founder and chairman of the French Bank of California, later known as the Bank of the West, and was finance chairman for Gov. Edmund G. Brown's business advisory committee.
He is survived by his wife, Charlotte; two daughters, Phyllis Stein of San Francisco and Charlotte Beyers of Palo Alto, Calif., and four grandchildren.
[Note: Unstated in this obituary is that Mr. Kempner was the first husband of Barbara H. Guggenheim, a daughter of Benjamin Guggenheim.]