The reaction rates of CO2 with an innovative CO2-capturing organic solvent (CO2COS), consisting of blends of 2-tert-butyl-1,1,3,3-tetramethylguanidine (BTMG) and 1-propanol, were obtained as function of BTMG concentration and temperature. A stopped-flow apparatus with conductivity detection was used. The reaction was modeled by means of a modified termolecular reaction mechanism which resulted in a second-order rate constant, and activation energies were calculated for a defined temperature range. Quantum chemical calculations at the B3LYP/6-31G(d) level also produced the activation energy of this reaction system which strongly supports the experimental findings.