Cuprous iodide (CuI) thin films with photoelectrochemical activity were prepared by anodizing copper wire or copper-electrodeposited tungsten wire in the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6 RTIL) containing N-butyl-N-methylpyrrolidinium iodide (BMP-I). A copper coating was formed on the tungsten wire by potentiostatic electrodeposition in BMP-dicyanamide (BMP-DCA) RTIL containing copper chloride (CuCl). The Cut films formed using this method were compact, fine-grained and exhibited good adhesion. The characteristic diffraction signals of Cut were observed by powder X-ray diffractometry (XRD). X-ray photoelectron spectroscopy (XPS) also confirmed the formation of a Cut compound semiconductor. The Cut films demonstrated an apparent and stable photocurrent under white light illumination in aqueous solutions and in a RTIL This method has enabled the electrochemical formation of Cut from a RTIL for the first time, and the first observation of a photocurrent produced from Cut in a RTIL. The coordinating strength of the anions of the RTIL is the key to the successful formation of the Cut thin film. If the coordinating strength of the anions of the RTIL is too strong, no Cut formation is observed. (C) 2012 Elsevier Ltd. All rights reserved.