ABSTRACTNonstoichiometric precursor-ratios for the synthesis of ZnS:Mn2+ are discussed and the significant influence on the luminescence features and crystal size is explained. From the temperature quenching of the ZnS photoluminescence a luminescence excitation model is proposed. Measurements of the photoelectrochemical properties of nanocrystalline ZnS electrodes doped with Mn2+ are also presented and discussed. The observation of both anodic and cathodic photocurrent is direct evidence for the nanocrystalline nature of the system. In-situ photoluminescence measurements showed stable Mn2+ related photoluminescence over a large potential range.