The open circuit voltage, fill factor, and power conversion efficiency ofn‐CdSe thin‐film electrodes for photoelectrochemical solar cells have been improved by treating the surface with Zn++ions. The overall efficiency of these electrodes was increased from ∼5% to as high as 6.5% with a soaking treatment in 1MZnC12. Photoelectrochemical measurement and Auger spectroscopy indicated the observed improvements were the result of a shift in the flat‐band potential to more negative values due to the incorporation of zinc into the surface region of the CdSe thin film.