We demonstrate that uniform dispersion of TiO 2 on graphene is critical for the photocatalytic effect of the composite. The hydrothermal method was employed to synthesize TiO 2 nanowires (NW) and then fabricate graphene-TiO 2 nanowire nanocomposite (GNW). Graphene oxide (GO) reduction to graphene and hybridization between TiO 2 NWs and graphene by forming chemical bonding was achieved in a one-step hydrothermal process. Graphene-TiO 2 nanoparticle (NP) nanocomposite (GNP) was also synthesized. Photocatalytic performance and related properties of NP, NW, GNP, and GNW were comparatively studied. It was found that by incorporation of graphene, GNP and GNW have higher performance than their counterparts. More importantly, it was found that NWs, in comparison with NPs, have more uniform dispersion on graphene with less agglomeration, resulting in more direct contact between TiO 2 and graphene, and hence further improved electron-hole pairs (EHPs) separation and transportation. The adsorbability of GNW is also found to be higher than GNP. The result reveals that the relative photocatalytic activity of GNW is much higher than GNP and pure NWs or NPs.