In the present study, photo-electrochemical and hydrogen evolution characteristics of a new type of TiO2(ns) and TiO2(ns)-In2O3/Ti septum based semiconductor-septum photo-electrochemical (SC-SEP, PEG) solar cell has been studied. The SC-SEP cell in the configuration of SCE/1 M NaOH/TiO2(ns)/Ti/H2SO4+ K2SO4/Pt-CE Pt-WE showed the photo-voltage and photo-current of 0.72 V and 8.6 mA/cm(2), whereas the SC-SEP cell employing In2O3 admired TiO2(ns) photo-electrode and having the configuration: SCE/1 M NaOH/TiO2(ns)-In2O3/Ti/H2SO4 + K2SO4/Pt-CE? PtWE, showed the photo-voltage and photo-current of 0.92 V and 14.6 mA/cm(2), respectively. The hydrogen gas evolution for the SC-SEP cell based on TiO2(ns)/Ti photo-electrode was found to be 8.2 1/h m(2), on the other hand the In2O3 modified TiO2(ns) exhibited a higher hydrogen gas evolution rate of 11.8 1/h m(2). Evidence and arguments have been put forward to show that the presence of In2O3 over TiO2 makes the system posses the advantages of a colloidal photochemical system. The better performance of the new photo-electrode is thought to be due to improved spectral response and catalytic activity of In2O3 in regard to the hydrogen gas evolution kinetics. (C) 2000 international Association for Hydrogen Energy.