Abstract: The present invention relates to a modified oligoester including an oligoester (1) that in one of its ends has a group that reacts with alcohols or organic acids forming covalent bonds and in one or more of its other terminations has one or more cyclic acetal groups (2). In addition, relates to the processes for the production of such modified oligoester, as well as the use of the same in the manufacture of polyester resins, coating compositions, and composite, as well as the process for producing these resins. The scope of the present invention is related to the chemical sector, particularly in what refers to modified oligoesters with cyclic acetal groups.