The Fiat CR.33 was a modified version of the CR.32 biplane fighter, with a more powerful engine and an increased top speed.
Some sources state that the first CR.33, serial number MM.296, made its maiden flight in 1935, the same year that saw the introduction of the CR.32bis.
Most sources don't mention this first prototype and instead place the maiden flight of the CR.33 in 1937.
All agree that it was powered by a 700hp Fiat A.33 R.C.35 engine and had modified landing gear. It could carry the same four machine guns as the CR.32bis, with two in the fuselage and two in the lower wings
The CR.33 achieved a top speed of 262mph and a range of 435 miles, giving it similar performance to the Fiat CR.42, the last of Celestino Rosatelli's biplanes to enter service. The CR.33 itself was not ordered into production, loosing out to the Fiat G.50 monoplane.