Ab initio calculations and a continuum model have been used to study the mechanism for formation of carbamate from CO2 and alkanolamines. The molecules studied are ethanolamine and diethanolamine. A brief review is also made of published experimental observations relevant to the reaction mechanism. The ab inito results suggest that a single-step, third-order reaction is the most likely. It would seem unlikely that a zwitterion intermediate with a significant lifetime is present in the system. A single-step mechanism also seems to be in good agreement with the experimental data.