The effect of the ionic liquid's (IL) anion type ([BIMIM][X], where X= [Br], [PF6] or [OctSO4]) and content on the morphology, surface properties and photoactivity of TiO2 obtained by solvothermal method has been systematically investigated. Our results revealed that the presence of [Br], [OctSO4] anions favor formation of anatase phase, while presence of [PF6] anion causes formation of mixture of anatase and Ti(OH)PO4 phases. The highest photocatalytic activity under visible radiation (approximately four times higher than pristine TiO2) was observed for the TiO2 sample grown in a presence of 1-butyl-3-methylimidazolium bromide for ionic liquid to TiO2 precursor molar ratio 1:2. Visible light induced phenol degradation was found to be realized mainly by oxygen radical anions, whereas the contributions of the other processes, involving reactions with trapped electrons, holes and hydroxyl radical, are limited in the overall reaction mechanism. Quantum chemical calculations concerning model of anatase vacancy suggest that charge transfer between the bromide anion and molecular oxygen interacting with the vacancy is a source of photoreactivity induced by visible photons.