A mathematical model for the computation of evaporation from bare saline soils is presented. Moisture flow and heat transport equations in the partially saturated zone of the soil are coupled at the soil surface with a lower atmosphere boundary layer model. The transport model considers multicomponent salt migration. The flow equation accounts for osmotic flux due to the presence of ion species in the soil solution. Nonlinear one-dimensional equations were solved using fully implicit finite difference schemes. The soil part of the model was tested using experimental data of water and solute redistribution under temperature gradients in sealed soil columns. In order to demonstrate the effect of soil salinity on the evaporation, the problem of water infiltration into soil with initially low water content and its subsequent evaporation was considered. Results show a significant effect of osmotic pressure gradients on predicted evaporation.¿ 1997 American Geophysical Union