Sulfonic acid-functionalized ordered nanoporous Na +-montmorillonite (SANM) was used as an efficient catalyst for N- tert-butoxycarbonylation of amines with di- tert-butyl dicarbonate under solvent-free conditions at room temperature. Various aliphatic, aromatic, heterocyclic amines and aminols were protected as their corresponding mono-carbamates in excellent yields and short reaction times. No competitive side reactions such as isocyanate, urea, and N, N-di-Boc formation were observed. The reported method is mild, chemoselective and has the advantages such as heterogeneous catalysis, low cost and the recyclability of the catalyst. Sulfonic acid-functionalized ordered nanoporous Na +-montmorillonite (SANM) was found to be a mild, novel, efficient and reusable catalyst for N- tert-butoxycarbonylation of amines with di- tert-butyl dicarbonate under solvent-free conditions at room temperature. Display omitted ► Synthesis of sulfonic acid-functionalized ordered nanoporous Na +-montmorillonite. ► Characterization and application of SANM for N- tert-butoxycarbonylation of amines. ► Catalysis under solvent-free conditions at room temperature. ► Heterogeneous catalysis and recyclability of the catalyst.