Polymerizable quality epsilon -caprolactam having an alkalinity of less than 0.05 meq. per kg. of lactam is produced in the improved disclosed process which includes extracting an aqueous lactam-rich solution with an organic solvent having a high distribution coefficient for the lactam with respect to the aqueous solution, and evaporating the lactam-rich organic solvent solution and recovering by distillation the lactam. Evaporation of the organic solvent requires considerably less thermal energy than evaporation of a similar aqueous solution.