A kinetic model has been developed to predict the distribution of wetness along a hollow fiber and the average wetness as a function of time in hollow fiber membrane (HFM) contactors. The membrane absorption experiments were conducted using the diethanolamine (DEA) solution as absorbent to absorb CO2 in polyvinylidene fluoride (PVDF) and polypropylene (PP) HFM contactors. The influences of operating conditions (such as solution concentration, temperature, liquid and gas flow rates) on the membrane wetting process in a HFM contactor were also investigated in experiments. The experimental data were fitted to the proposed kinetic equations. The fitting results indicate that the proposed kinetic equation successfully described the membrane wetting process and prove that the membrane wetting rate was controlled by the solute adsorption on the bare pore wall. Therefore, this model may provide support for the design of membrane contactors suffering from membrane wetting.