Abstract: A process for producing an epoxy-group terminated polyoxazolidinone comprising the copolymerization of a polyisocyanate compound (A) with two or more isocyanate groups with a polyepoxide compound (B) with two or more epoxy groups in the presence of a specific catalyst (C), wherein the molar ratio of the epoxy groups of the polyepoxide compound (B) to the isocyanate groups of the polyisocyanate compound (A) is from 2.6:1 and less than 25:1, and wherein the copolymerization is operated in the absence of an additional solvent (D-1) with a boiling point higher than 170° C., preferred higher than 165° C., more preferred higher than 160° C., and most preferred higher than 150° C. at 1 bar (absolute). The epoxy-group terminated polyoxazolidinones resulting from the process are also provided.