The aim of the present work is to carry out parametric analysis of unsteady combustion of composite propellants taking into account all the experimentally observed phenomena. The theoretical analysis is based on the time scale analysis of pressure transient, propellant, condensed phase reactions, gasphase and ammonium perchlorate particle size. Three influence factors relating to gasphase heat feed back and condensed phase energy release are used as independently variable parameters. The influence of each of these influence factors on the predicted dynamic burning rate is found. A mechanism of unsteady combustion of composite propellant subjected to rapid depressurization is postulated. The predicted dynamic burning rates are compared with the available experimental results. © 1982 Taylor & Francis Group, LLC