ZnS thin films that are used as buffer layers in thin film solar cells are usually deposited by chemical bath deposition using hydrazine hydrate as a complementary complexing agent. This material is, however, highly hazardous and its replacement by a less-hazardous material is desirable. In this work thin films of zinc sulfide have been deposited using sodium citrate as a novel complementary complexing agent and experiments performed to determine the optimum conditions for producing conformal films, free from pinholes. The layers deposited were found to consist of Zn and S but with a small concentration of O present. Data relating to how the deposition conditions affected the physical properties of the deposited layers are reported.