A new approach for the electrosynthesis of indium sulfide films is described. This approach uses a sulfur-modified gold substrate, and relies on the underpotential deposition of indium on it to form an indium sulfide alloy. Combined cyclic voltammetry and electrochemical quartz crystal microgravimetry scans demonstrate the veracity of this film growth approach. Photoelectrochemical measurements in a polysulfide redox medium show that the In2S3 layers thus grown are photoactive and behave as an n-type semiconductor.