Spray pyrolysis, an aerosol decomposition technique, was first used to synthesize ZnS:Mn2+ particles, and their optical properties were characterized. The effects of process parameters on the properties of ZnS:Mn2+ particles were systematically investigated for Mn2+ doping concentrations of 0-8 at. %. The results show that a number of parameters such as temperature, cationic source, doping concentration, solution composition, and concentration can affect particle morphology, crystalline phase, crystallinity, and thus the photoluminescence of the products. Micrometer/submicrometer particles have spherical shapes and dense microstructures. Excitation/emission bands and intensities are largely dependent on the synthesis temperature employed. The effects of different precursors on the product particles and photoluminescence were also investigated. Some of the phenomena observed differed from other reports. The mechanisms by which various process conditions affect particle morphology, crystalline phase, and luminescent property are discussed.