The present paper reports a study about entropy generation analysis for the case of chemical absorption of a gas into laminar falling liquid film. The CO2 absorption into monoethanolamine (MEA) aqueous solutions has been considered. Temperature and concentration expressions are determined by using Laplace transform and used for the entropy generation calculation. The effects of irreversibilities due to heat transfer, mass transfer, viscous effects, coupling effects between heat and mass transfer, and chemical reaction on the total entropy generation of the considered system are derived. The obtained results show that entropy generation is mainly due to chemical reaction irreversibility at the gas–liquid interface. Between this interface and the reaction film thickness (where the reaction take place), entropy generation is due to both chemical reaction and mass transfer irreversibilities. More details concerning the contribution of each kind of irreversibility to entropy generation through the falling film are graphically presented and discussed.