Massi was born in Baboua, Nana-Mambéré Prefecture. He was President of the Committee for Information and the Defense of Democracy, which he founded on November 17, 1991. After the victory of Ange-Felix Patassé of the Movement for the Liberation of the Central African People (MLPC) in the August 1993 presidential election, Massi joined the government of Prime Minister Jean-Luc Mandaba as Minister of Energy and Mineral Resources in October 1993, remaining in this position until June 1996. On February 6, 1997 he became Minister of Agriculture and Animal Husbandry.