the invention relates to novel collagen peptides that are modified by grafting free or substitued thiol functions carried by mercaptoamine radicals . the aim of the invention is to provide thiol collagens that can be cross - linked in a sufficient and controlled manner by forming s — s bridges and which are biocompatible . this is achieved by means of the inventive thiol collagens which are characterized in that the mercaptoamine radicals are identical to or different from each other and are exclusively grafted on the aspartic and glutamic acids of the collagen chain by amide bonds . the invention also relates to a method for the production of said thiol and cross - linkable collagens . the novel modified cross - linkable and / or cross - linked collagens can be used as biomaterials .