Trapping of light‐generated holes in copper‐doped CdS is important to the operation of the thin‐film CdS/Cu2S solar cell. Consequently, there is interest in determining the distribution of the hole traps both in energy and inx, the depth from the junction. Capacitance transients are a useful probe of the depth dependence of trapped hole density,pT(x), since capacitance can be related by electrostatic theory to depletion layer width and charge density. It is shown from variation of capacitance in 1‐cm2thin‐film CdS/Cu2S solar cells, prepared at the Institute of Energy Conversion with temperature, heat‐treatment time, infrared quenching, and illumination intensity, that the observed photocapacitance is characteristic of copper impurity centers in CdS. Measurements of photocapacitance decay in these cells following abrupt shutoff of intense blue light show a time dependence different from that predicted by the usual theoretical treatment ofp–njunctions. This starts from the assumption of a uniform fixed‐charge density and leads to a prediction thatC2−C2∞decays exponentially with time, whereC∞is the dark capacitance. The theoretical relations have been rederived using apTvarying as exp(−x/d), wheredis a distance characteristic of the depth dependence. The resulting expressions predict thatpTshould vary asC−2∞−C−2. It is shown that this relation is closely satisfied by the measured photocapacitance transient data for temperatures from 77.5 K to ∼190 K, for times up to several tens of seconds, and for shorter times at higher temperatures. It is pointed out that some other dependence which confines the trapped hole density near the junction could equally well be used to fit the data. Possibilities for the physical origin of this depth dependence are discussed. It is shown that the relation of electric field at the junction to the measured capacitance derived from this model gives better agreement with measurements of the variation of collection efficiency with illumination intensity.