A series of tetraalkylammonium catalysts immobilized on polystyrene or carbon nanotubes were investigated in a reaction between alkyl halides, amines, and CO 2 . The yield of carbamates was up to 85 % at 100°C and 1 MPa of CO 2 after 3 h (first stage 25°C, 1 h) in the presence of Cs 2 CO 3 and DMF as a solvent. The best results were achieved in the case of large ammonium substituents (C 4 and C 6 ) in the catalyst, benzyl amine, and benzyl chloride as reagents. The catalysts retained their activity after at least five cycles when carefully dried between cycles. Both polymer and carbon nanotube supports were equally effective, but the latter were less prone to deactivation. Graphical Abstract