The main drawback of conventional alkanolamines for post combustion CO2 capture is that they cannot combine a low energy consumption for regeneration and a high reactivity. Blends of tertiary and primary amines provide these two advantages at the same time. This study considers a new composition of solvent for carbon capture: methyldiethanolamine (MDEA) 30 wt.% and hexylamine (HA) 10 wt.%. MDEA acts as regeneration promoter and HA as activator. The kinetics of this solvent is assessed through an optimization method based on a genetic algorithm and at different temperatures (25 °C, 40 °C and 60 °C), in order to determine the Arrhenius law. The reaction considered is a first order reaction where each amine reacts with CO2 in parallel. The composition studied does not give better results than MDEA alone. This is probably due to the addition of a too large amount of hexylamine.