Development of the A.100 was in response to a Czechoslovak Air Force requirement of 1932 for a uniform replacement for the A.11s, Aero Ap.32s, and Letov Š.16s then in service.

Nevertheless, since the only other competitor for the air force contract, the Praga E.36, had not flown by the close of tenders, the A.100 was ordered for production.

),[3] first flying in December 1934, this type served in the Spanish Civil War curiously on both sides of the conflict.

Further development led to Aero Ab.101 (enlarged hull and wings plus Avia Hispano Suiza HS 12 Ydrs engine rated 860 h.p.

Final stage of the development was Aero A.104, where Ab.101 was converted to a high-wing monoplane with enclosed cockpit, only one prototype was built in 1937.