Photoelectrochemical measurements (PECMs) of CuInS2 (CIS) nanocrystal films (NCFs) on indium-doped tin oxide coated polyethylene terephthalate were carried out in an electrolyte solution. Intensity modulated photocurrent spectroscopy (IMPS) was performed at the NCF/solution interface. IMPS quantified the kinetic constants of the photoreaction. The rate ratio of the product separation to recombination increased as a function of applied potential, while the RC time constant decreased. Interfacial reaction kinetics of MV2+ and the OS film was revealed by means of PECMs and IMPS. The interaction of the light absorbing CIS NCFs at a hole-rich interface allow for an understanding of what might happen at an analogous n-type junction. (C) 2014 Elsevier B.V. All rights reserved.