As part of our continuing investigations into the problem of pre-reaction in MOCVD systems, layers of ZnS have been grown onto GaAs substrates using Me₂Zn and the novel sulfur-containing precursor propylene sulfide. Layers have been produced in the temperature range 300–550 °C and have been characterized by XRD. The results indicate that the layers with the highest degree of crystallinity are grown towards the higher end of this temperature range. Most significantly, no pre-reaction is observed between these precursors.