Pyrolysis characteristics of a mixture consisting of PVA-coated AN and chromium compounds as burning modifiers have been investigated in detail at pressures ranging from 0.1 to 5 MPa by means of DTA, DSC and TG. It has been found that the encapsulation of AN by PVA hardly affects pyrolysis characteristics of AN alone and AN with chromium compounds as burning accelerator. Chromium compounds enhance the pyrolysis reaction of AN by the following order; (NH4)(2)Cr2O7 greater than or equal to (NH4)(2)CrO4 > Cr2O3, but they do not affect the pyrolysis of GAP fuel-binder. The effects of chromium compounds on the burning rate of PVA-coated AN/GAP propellant have been examined. They enhance the burning rate of the propellant at pressure up to 7 MPa. Chromium oxide and ammonium dichromate would have a significant effect on the gas phase reaction and on both condensed-phase and gas phase reaction, respectively. GAP is also considered to promote the condensed-phase reaction during combustion.