The vacuum deposited thin films of n-CdSe0.7Te0.3 of 5000 Å thickness have been characterized by X-ray diffraction (XRD) for structural analysis, by energy despersive analysis of X-rays (EDAX) for compositional analysis and the scanning electron microscopy (SEM) for surface studies. Similar films have been deposited on Indium Oxide precoated microslide glass plates and the photoelectrochemical properties of n-CdSe0.7Te0.3/polyiodide junction are investigated for suitability for solar energy conversion by I-V measurements in the dark. Also, the carrier concentration and flat band potential have been calculated from the space charge capacitance vs voltage measurements. The minority carrier diffusion length, Lp has been determined using Gärtner's model. Using the Mott-Schottky plots, the energy band diagram at flat band condition has been constructed. The occurrence of high quantum efficiency and high power conversion efficiency have been explained.