Abstract Information is required on the heat of absorption for the correct design and optimization of absorption processes for the removal of CO 2 from gas streams. The heat of absorption affects the temperature profile in the absorber, and consequently the capacity of the absorption unit and the achievable purity of the gas from which CO 2 is removed. It is also associated with the energy requirement of the stripper. This usually accounts for the greatest operating cost in the absorption process, and if the amine could be regenerated using less energy or with low-grade energy, i.e. waste heat (70–90 °C), significant savings could be made. This paper presents experimental data on the heat of absorption of CO 2 in solutions of 2-amino-2-methyl-1-propanol (AMP) and an organic solvent, either N-methyl-2-pyrrolidone or triethylene glycol dimethyl ether, at different amine concentrations (15 wt% and 25 wt%) and temperatures (25 °C and 50 °C). The heat of absorption was greatly affected by the formation of a precipitate, which was observed during some of the experiments, and was significantly lower at CO 2 loadings above 0.5 mol CO 2 /mol AMP, as physical absorption of CO 2 became the dominating absorption process.