The present invention relates to halogen-free flame retarded thermoplastic moulding compositions based on a polyester resin, a process for their preparation and halogen-free flame retarded corresponding articles.The composition according to the invention comprises at least from 0.1 to 30% by weight of aluminium hypophosphite as halogen free flame retardant additive, in case in addition to a mixture of other halogen free flame retardant additives and at least from 5 to 95% by weight of a polymer based on polyester, particularly a linear polyester resin.