A model that considers the Navier-Stokes equations is used to study the influence of surfactants, substances that improve heat and mass transfer in absorption machines due to Marangoni effect. For solving the free surface location a surface tracking method is used, and for the calculation of surface tension forces, a continuum surface forces model is employed. The coupled equations are solved using the SIMPLEC procedure. Two common surfactants for LiBr aqueous solutions, 1-octanol and 2-ethyl-1-hexanol, are numerically tested and the absorption enhancement produced in a stagnant pool is compared with other researchers' results. For falling film absorption some other results are showed. (C) 2004 Elsevier Ltd. All rights reserved.