A process for producing thermoplastic polyoxazolidinone, comprising the following steps: (i) Reaction of a diisocyanate compound (A) with a bisepoxide compound (B) in the presence of a catalyst (C) and a compound (D) in a solvent (E) forming an intermediate compound (F) and (ii) Reaction of a compound (G) with the intermediate (F) formed in step (i), wherein compound (D) is one or more compounds selected from the group consisting of monofunctional isocyanate and monofunctional epoxide, and wherein compound (G) is an alkylene oxide. The invention is also related to the resulting thermoplastic polyoxazolidinone.