GAPTRIOL is a non-linear glycidyl azide polymer used as the starting material to produce a binder in composite propellant formulations. The mechanism and energetics for the decomposition of GAPTRIOL are therefore of interest. Accordingly, this paper reports results of DSC, TGA and ARC measurements on GAPTRIOL. Discussion of these results and comparison with literature results for GAPDIOL, the linear analogue, are included. The decomposition of GAPDIOL has been reported as a first-order process. Results of kinetic studies on GAPTRIOL using both variable heating rate and isothermal techniques suggest that its decomposition is not a first-order process. In addition, TGA data show a two-stage weight loss in nitrogen and a four-stage weight loss in air. The kinetic information gleaned from the DSC and TGA measurements is compared with that extracted from the ARC data.