A new method for prediction of Gurney velocity of explosives is introduced in which energy output is correlated with the heat of detonation,the number of moles of gaseous products of detonation per gram of explosive and the average molecular weight of gaseous products. It is assumed that the CHNO explosive reacts to form products composed of N2,CO,H2O,CO2,H2,O2 and C(s) as determined by the oxygen balance of the unreacted compound. Good agreement is obtained between measured and calculated values of Gurney velocity as compared to previous correlations which assumed the reaction products to consist of N2,H2O,CO2 and either C(s) or O2.