The stability to detonation and the expansion behavior of reaction products were studied for an aluminized explosive, HBX-1. The detonation velocity-charge diameter and detonation velocity-loading density relationships were determined by streak camera techniques and electronic probe methods. These data gave reaction zone lengths which increase from 0.07 mm for an initial explosive density of 1.72 g/cc to 1.5 mm at 1.3 g/cc. With the pressure- particle velocity relation established from 338,000 bars to 15 bars, and conditions in the C-J state (PCJ = 220.4 kbars) specified, the generalized hydrodynamic relations derived by Jones were used to evaluate the constants in an empirical equation of state and in the Wilkins equation of state as modified by Allan and Lambourn.