Pyrrolidinone was identified in food and tobacco samples by gas chromatography combined with NO-specific chemiluminescence detection (TEA). Up to 77 mg/kg pyrrolidinone were detected in cocoa powders, coffee, coffee surrogates, dried vegetables and tobacco leaves. When treated with excess nitrite under acidic conditions, N-nitrosopyrrolidinone was formed in concentrations up to 44 mg/kg. The nitrosation characteristics of pyrrolidinone indicate its possible conversion to nitrosopyrrolidinone under conditions of the gastric tract.