The capacitance‐voltage (C‐V) and the current‐voltage characteristics of metal/ZnSe/p‐GaAs capacitors have been investigated; both epitaxial layers were grown by molecular beam epitaxy. In the capacitor structures highly resistive, stoichiometric ZnSe functioned as the pseudoinsulator on the doped GaAs layers. The capacitance‐voltage measurements demonstrated that the capacitors could be biased from accumulation through depletion, and into deep depletion, with current in the range of 10−8A cm−2. Very little frequency dispersion was observed in theC‐Vdata when measured from 1 kHz to 1 MHz. From the high‐frequencyC‐Vcurve, the surface state density as a function of position in the GaAs band gap was determined. Surface state densities were comparable to densities reported for (Al,Ga)As/GaAs heterojunctions.