A cylindrical corundum‐filled resonator of the TE112‐type in the microwaveXband, coupled to a coaxial line, is used in two systems designed for the high‐pressure, low‐temperature electron paramagnetic resonance (EPR) studies. The first one is used up to 800 MPa and over a temperature range of 80–400 K. The second permits EPR measurements down to 4 K in the pressure range below 400 MPa. Pressure and temperature can be simultaneously varied and controlled with the high accuracy needed to study spectral anomalies in the vicinity of the phase transitions in solids. ©1996 American Institute of Physics.