The Photo-electrochemical studies on chemically deposited Cd-1-xHgxSe thin films (0 <= x <= 1) have been carried out to assess its suitability for use in conversion of solar energy to electrical energy. The PEC cell with Cd-1-xHgxSe thin films as photoanode and sulphide-polysulphide (0.5 M) solution as electrolyte have been constructed and investigated for various cell parameters as a function of photoelectrode composition parameter (x). The film with composition x = 0.4 (Cd0.6Hg0.4Se) showed enhanced solar to electrical conversion efficiency (eta) and fill factor (ff). The observed enhancement has been correlated to decrease in photoelectrode resistance and band gap (E-g). The addition of Hg in CdSe, to certain limit, showed better performance and stability of the cell. (C) 2007 Elsevier B.V. All rights reserved.