Hot isostatic processing (HIP) is the latest method to produce open porous materials, such as ceramics or metals. In this review paper, features and applications of HIPed porous materials are described. Sintering behavior under high pressure gas is also discussed in order to understand how porous materials are obtained by this method. HIPed porous materials have higher open porosity, higher mechanical strength, narrower pore size distribution and higher fluid permeability than conventionally sintered ones. These excellent properties of HIPed porous materials are due to the enhanced surface diffusion caused by the high gas pressure. By applying these excellent properties of HIPed porous materials, filters, grinding wheels, and porous electrodes for electrochemical analysis can be produced with better properties than products made by conventional sintering.