As far as can be determined, linguist Joseph Roye Applegate was the first appointed black faculty member at MIT. He was considered an expert in the Berber language of southwestern Morocco. In 1955, Applegate joined the MIT Research Laboratory of Electronics (RLE) as faculty to work on machine translation and mathematical studies of grammar. 

Two of us got our degrees [from the University of Pennsylvania] in 1955, Noam Chomsky and I. We immediately moved into positions at MIT, and part of the position for me was teaching German as well as working on the machine translation.

Joseph Applegate in Technology and the Dream by Clarence G. Williams (MIT Press, 2003)