The hydrogen production activity was in the order H Nb O /(Pt, TiO ).HNbO /Pt.TiO /Pt.H Nb O /TiO .HNbO.TiO . The photocatalyst possessing high hydrogen evolution activity such as H Nb O /(Pt, TiO ), H Nb O /Pt, TiO /Pt and H Nb O /TiO showed no noticeable nitrate reduction activity. Consequently, only TiO and H Nb O showed the nitrate ion photoreduction activity under near UV-visible light (l.290 nm) irradiation in the presence of methanol as sacrificial hole acceptor.