A 1933 development of the Š.31 with a new wing profile, the aircraft is open cockpit and radial engine with a separate exhaust collector ring and Townend ring cowling. Power was a 550 hp Bristol Mercury.
The single-bay wings have N-type interplane struts and centre section struts.
Only one prototype and 23 production examples were produced, and the Š.231 was briefly used by the 35th and 36th Squadrons of the 2nd Air Regiment of the Czechoslovak Air Force.
Characteristics being somewhat short of the desirable and an opportunity presenting itself to cut losses, the fighter was withdrawn, crated and shipped to Spain where circumstances were dictating a more generous attitude to the shortcomings of flying equipment. In Spain, it was assigned to the 2a Escuadrilla of the Grupo de Gaza nüm 71 of the Republican air arm. The operational career of the š -231 was to be less than outstanding in Spain, a number being lost in training accidents and lack of spares back-ing resulting in something of a nightmare for the maintenance personnel.