The invention relates to a method for producing propylene during which a first gas mixture, which is technically free of oxygen but contains propane, water vapor and hydrogen, and which has a temperature of at least 400.degree. C., is led into a reaction device having at least one catalyst bed as well as usual dehydration conditions. Another gas mixture, which contains propane and oxygen and which can also contain ammonia, the propane content exceeding the oxygen content, is led into the same reaction device in which it reacts with the first gas mixture while forming propylene, water vapor and hydrogen, and the formed gas mixture containing propylene, water vapor and hydrogen is drawn out of the reaction device.