Atomic layer deposition is used to deposit crystalline anatase TiO₂ on 500 nm silica support particles over a range of shell thicknesses. The core–shell morphology combines nanometer thickness titania with silica that is readily separable from liquid media. The composite particles are evaluated as photocatalysts for destruction of the model pollutant methyl orange and, after deposition of platinum co-catalyst, for the sacrificial generation of hydrogen from water. The catalytic activities normalized to surface area are higher than those of P25 mixed anatase/rutile titania nanoparticles.