A thermodynamically consistent equation of state (EOS) was developed for unreacted, single-crystal ammonium perchlorate (AP) for shock compression along the [210] and [001] directions. The specific heat,cv,the pressure-temperature coefficient,(∂P/∂T)v,and the isothermal bulk modulus,BT,were determined from Hugoniot and isothermal compression curves, along with available data at atmospheric pressure. The mechanical response of each orientation of the AP crystal was modeled as an isotropic elastic-plastic solid. Above the HEL, the rate dependent yielding of AP was described with a simple overstress model. Time-resolved Raman spectroscopy experiments were carried out to obtain temperatures in the shocked state. These temperature measurements were used to constrain the values of various EOS parameters. ©2000 American Institute of Physics.