A simple non-destructive method based on ac reluctance measurements is proposed to determine the Curie temperature of air-sensitive magnetic materials. The set-up is used for the rapid evaluation of T C of vanadium-chromium Prussian blue analogues of general formula A x C y V I I α V I I I ( 1 - α ) [Cr(CN) 6 ] z (A=iodide, sulphate; C=potassium, tetrabutyl ammonium) whose Curie temperature lies in the vicinity of room temperature.