DFT calculations using a PCM solvation model were carried out to examine the reaction pathways for the formation of carbamate from CO2 and monoethanolamine (MEA) in the presence of an additional proton acceptor, MEA or H2O. In both cases, the zwitterionic species [HO(CH2)(2)NH2+-COO-] has a lower energy than the reactants. Proton transfer from the zwitterionic species to the base (MEA) produced a carbamate product with an accompanying gradual decrease in energy. However, a similar process for the water case resulted in an implausible increase in energy, which suggests that MEA is suitable as a base but H2O is not.