Gas phases of ethylene oxide and propylene oxide, commonly used for technical alcoxylation reactions, can decompose explosively with an enormous temperature and pressure rise even without the presence of air. For the estimation of consequences of such reactions explosion pressures and rates of pressure rise of EO and certain mixtures of ethylene oxide and propylene oxide at temperatures between 100 degrees C and 200 degrees C and pressures between 1 bar and 10 bar were determined experimentally using vessels with volumes of 3 dm(3) and 100 dm(3).