Graphitic carbon nitride (g-C3N4) has attracted much attention as a metal-free semiconductor having visible-light absorption and relatively high chemical stability. In the present study, we hybridized g-C3N4 with sulfur-doped TiO2, which is a visible light-responsive photocatalyst with high oxidation ability, in order to improve photocatalytic activity under visible-light irradiation. Hybrid photocatalysts were prepared by three methods: agate mortar, sonication, and planetary mill. Activities of the hybrid photocatalysts depended on the mixing method. The sample prepared by a planetary mill showed the highest photocatalytic activity, 4-times higher than that of sulfur-doped TiO2. We concluded that the high activity of the hybridized sample under visible-light irradiation is induced by charge transfer between the two photocatalysts mimicking the Z-scheme in photosynthesis. (c) 2013 Elsevier B.V. All rights reserved.