Flexible polyester film is coated with a silicone release coating by applying and curing a solventless composition which comprises a polydiorganosiloxane having solely in its terminal units hydroxyl or alkenyl groups, an organohydrogen siloxane crosslinker and a catalyst which is preferably a Pt compound. The ratio of SiH groups over the hydroxyl or alkenyl groups is at least 2/1. The release coating adheres well to the polyester film without the need to pretreat the film with electron beam irradiation.