This work was originally motivated by the search for high-temperature piezoceramic materials with low acoustic impedance and high electromechanical coupling. The temperature and pressure behavior of two PZT-based materials with engineered porosity, Pz31 & Pz36 developed by Meggitt A/S, were studied. We considered operating environments of up to 200°C and 20,000 psi. Previous experimental results show that these two materials performed well at temperatures up to 175°C under normal pressure. However, both materials tend to depole by pressure cycling up to 15,000 psi. To develop insight into the depoling mechanism, we continued the study using the densified counterparts of these materials, Pz24 & Pz26 respectively. The experimental results clearly showed that the dense materials are not degraded under pressure. A bismuth titanate-based material, Pz46, with a high Curie temperature, was also investigated as part of this study to extend the operating temperature limit beyond 175°C. © 2013 IEEE.