► TeO2 crystals are good bolometer for neutrinoless double beta decay search. ► Up to now alpha background cannot be distinguished in TeO2 bolometers. ► We detected light from TeO2 crystals which allows alpha background rejection. ► The light can be explained as due to Cerenkov emission. TeO2 crystals have proven to be superb bolometers for the search of neutrinoless double beta decay in many respects. However, if used alone, they do not exhibit any feature that allows to discriminate an α energy deposit from a β/γ one. This fact limits their ability to reject the background due to natural radioactivity and eventually affects the sensitivity of the search. In this paper we show the results of a TeO2 crystal where, in coincidence with its bolometric heat signal, also the luminescence light escaping the crystal is recorded. The results show that we are able to measure the light produced by β/γ particles, which can be explained as due to Cerenkov emission. No light is detected from α particles, allowing the rejection of this background source.