AbstractIntrinsic viscosities inm‐cresol and weight average molecular weights,M̄w, were measured for samples of high molecular weight poly(2‐pyrrolidone) (poly (1)) prepared by anionic polymerization of 2‐pyrrolidone (1) accelerated with CO2. It was proved that the earlier found relationship [η] = 4 · 10−2·M0,77(in cm3· g−1) holds for M̄Mwup to 8 · 105g. mol−1. The probable reason for the formation of poly (1) with an exceptionally high molecular w