The Potez 31 was designed to meet the requirements of the 1925 C2 programme calling for a two-seat night fighter and diurnal reconnaissance-fighter. Not flown until 1929, and closely resembling the Potez 25M monoplane variant of the Potez 25 army co-operation biplane, the Potez 31 was a parasol monoplane of wooden construction with fabric covering. Embodying the facility developed for preceding types of accepting either Hispano- Suiza or Lorraine-Dietrich W-type water-cooled engines, the Potez 31 was tested with both the 500hp HS 12Mb and the 450hp L-D 12Eb. Armament consisted of two fixed forward-firing 7.7mm guns, two similar weapons on a flexible mount in the rear cockpit and a fifth gun firing through a hatch in the rear cockpit floor. Development of the Potez 31 was terminated with the discontinuation of the C2 programme.