The comparative analysis of the influence of the effect of non-linear mass transfer and the Marangoni effect on the mass transfer kinetics and the hydrodynamic stability are done. Co-current gas and liquid flow in the laminar boundary layer along the flat phase surface is considered. One of the components of gas is absorbed by the liquid and reacts with a liquid component. The chemical reaction rate is of first-order. The heat effect from the chemical reaction creates a temperature gradient, i.e. the mass transfer together with a heat transfer can be observed. The data for heat and mass transfer coefficients are obtained. The critical Reynolds numbers, corresponding wave velocities, and wave numbers are obtained. (C) 1997 Elsevier Science Ltd.