A new technique for the synthesis of multiphase photocatalysts Cd1-xZnxS/ZnS with hydrothermal treatment has been proposed. Photocatalysts were characterized by different techniques including XRD, low temperature N2 adsorption, and UV-vis spectroscopy. The activity of synthesized photocatalysts was tested in the photocatalytic hydrogen evolution from water solutions of Na2S/Na2SO3 under visible light irradiation (λ = 450 nm). It was shown that the hydrothermal treatment of Cd0.3Zn0.7S lead to the formation of multiphase Cd0.6Zn0.4S/ZnS and increased the activity by a factor of 8.7. The highest exhibited rate of hydrogen evolution on the composite photocatalyst was 8 mmol g-1 h-1.