This work presents an investigation of local gas side overall mass transfer coefficient (KG) of the membrane gas absorption process determined from CO2 concentration gradients. The experimental KG was compared with simulation results of non wetted and partially wetted modes of operation from a plug flow and rated based model to study the effects of various operating parameters on the partial wetting of the membrane and its process performance. The experiments were performed using two types of membranes (polytetrafluoroethylene, PTFE and polyvinylidene fluoride, PVDF), and two absorbents (monoeLhanolamine, MEA and 2-amino-2-meLhyl-l-propanol, AMP). A comparison showed that the membrane wetting fraction was lowest at the liquid outlet and varied along the length of the membrane module clue to the effect of pressure drop. The effect of liquid velocity on membrane wetting was very obvious at a low membrane wetting fraction whereas it was less noticeable at a higher membrane wetting fraction. The average membrane wetting fractions were lower when PTFE was used with MEA solution than when PVDF and AMP solutions were used in experiments. In addition, the results further showed that the use of CO2 loaded MEA solution could significantly reduce membrane wetting. (C) 2015 Elsevier B.V. All rights reserved.