Disclosed is a method for producing a catalyst containing vanadium, phosphorus, and oxygen, which is used for oxidizing the gas phase of a hydrocarbon having at least four carbon atoms to maleic anhydride. According to the inventive method, a corresponding catalyst precursor which contains vanadium, phosphorus, and oxygen and is provided with particles having an average diameter of at least 2 mm is converted into a catalytically active form by means of calcination, and a flow of the catalyst precursor is transported on a conveyor belt across at least one calcination area over a distance 1.sub.n at an essentially steady speed in order to be calcinated. The variation over time of the gas temperature in relation to the set point value amounts to .ltoreq.5.degree. C. at each position in the area of the flow of the catalyst precursor, which lies within the second half 1.sub.n/2 of the calcination area, while the local difference in the gas temperature between any positions in the area of the flow of the catalyst precursor, which is located within the second half 1.sub.n/2 of the calcination area, amounts to .ltoreq.5.degree. C.