Photoelectrochemical (PEC) solar cells made using as-grown polycrystalline thin films of n-CdSe0.6Te0.4 (thickness ≈ 5000 Å) (prepared by vacuum thermal flash evaporation with a deposition rate of 20 ± 1 Å s-1 in a vacuum better than 5 × 10-5 torr on indium oxide coated microslide glass plates [σ = 1.25 × 104 (Ω-cm)-1] held at 200°C) dipped in aqueous ferro-ferricyanide electrolyte have been studied to evaluate the conversion efficiency under white light illumination intensity of 100 mW cm-2 (AM1). Mott - Shottky plots have been drawn (in the dark condition) to evaluate the semiconductor parameters. The reasons for the observed high power conversion efficiency and high quantum efficiency in relation to the semiconductor parameters are explained. The films have been characterized by X-ray diffraction for structural studies, Energy Despersive Analysis of X-rays (EDAX) for compositional analysis, Scanning Electron Microscopy (SEM) technique for surface morphology studies and optical absorption for band gap determination. © 1997 Elsevier Science Ltd.