Two simple correlations are proposed for the prediction of the specific impulse (I-sp) of propellants and the Gurney velocity (root 2E(G)) of high explosives. It was found that the oxygen balance (OB) correlates well with experimental (root 2E(G)) for 24 types of explosives and (I-sp) values for 22 monopropellants and propellants formulations obtained from ISPBKW thermochemical code. The results show that most of the estimated values do not deviate more than 4% for (root 2E(G)) and 3% for (I-sp) when compared to experimental and ISPBKW code output and that the new relationships are suitable for engineering calculations where experimental or complex predictive methods are not available.