An integral rate-based model is used to find a quick and reliable estimate of the height of packing in a CO2-alkanolamine absorber. Heat transfer in the gas phase is neglected. Due to the need to arrive at a quick estimate of the height of packing, this assumption is made. Starting from the bottom, the height of packing required for a small change in Solute mole fraction in a differential section of the tower is calculated. An average of the enhancement factor calculated using film. theory of mass transfer accompanied by chemical reaction for each boundary, is used. These calculations are repeated at the top of the tower, the desired solute concentration is reached. The Cumulative height gives total height of packing. required. The method is illustrated.