A novel In3+-doped TiO2 and TiO2/In2S3 nanocomposites for photocatalytic degradation of environmental pollutants and stoichiometric degradation of warfare agents were prepared by a homogeneous hydrolysis with urea and thioacetamide, respectively. The prepared samples series TiInTAA were annealed at 600°C. The prepared samples were characterized by X-ray powder diffraction, IR spectroscopy, Raman spectroscopy, specific surface area (BET) and porosity determination. The method of UV–Vis diffuse reflectance spectroscopy was employed to estimate band-gap energies. The photocatalytic activity (PCA) was tested by degradation of Orange dye, whereas stoichiometric activity was studied by degradation of sulfur mustard. Incorporation of In3+ into titania lattice increases PCA of TiO2 in the visible light and increases stoichiometric decomposition of sulfur mustard against nondoped TiO2 as well. PCA of TiO2/In2S3 composite depends on the optimal ratio of TiO2:In2S3 in composite, while the activity for stoichiometric decomposition of sulfur mustards depends on the content of In2S3 in nanocomposite.