Abstract The aminolysis and the effect of water on the aminolysis processes of n ‐methyl β ‐sultam have been studied using density functional theory (DFT) method at the B3LYP/6‐31G* level. The stationary structures and energies have been investigated for both reactions to find two different reaction channels. Specific and general solvent effects have been evaluated and the most favored pathway was found. The presence of solvent disfavors the reaction, whereas the participation of water in the aminolysis reaction plays a positive role and reduces the activation energy greatly. All transition states in the assisted aminolysis are 35–70 kJ/mol lower than those for the non‐assisted reaction.