Chemical, thermal and mechanical stability are important parts in the quality and safety assessment of propellants and explosives. Decomposition reactions limit the safe use time, the socalled lifetime. With explosives consisting of nitric acid esters, stabilizer consumption and molar mass (molecular weight) decrease are very suitable methods to predict the safe of use time or the remaining safe lifetime. Kinetic models for stabilizer and molar mass decrease are presented and the prediction methods discussed. A new model for stabilizer depletion, a combination of of first and zero order reaction, describes the decrease very good and the prediction of the lifetime is improved. The Arrhenius parameters for stabilizer consumption and molar mass decrease of gun and rocket propellants are given. Propellants produced with crystalline explosives and polymeric binders are more stable against thermal stress, but they also decompose exothermally at elevated temperatures. Important safety paramet ers of these materials are (i) the temperature of the beginning of the exothermal decomposition, (ii) the following adiabatic self heating with the characteristic heat rate and (iii) the pressure rate if the substance decomposes with gas evolution. Such data are shown for some explosive materials.