The origin of the visible-light absorption of main-group element (C, N, S) doped TiO2 nanostructures is investigated via diffuse reflectance and valence band X-ray photoelectron spectroscopy. The synthesized C-, W, and S-doped titania nanomaterials show an increased electron density of states,above the valence band of TiO2, which explains the red-shifted light absorption of these potential photocatalysts and simultaneously suggests a lowered potential as photooxidants; compared to Degussa P25 TiO2.