A new simulation model for simultaneous heat and mass transfer combined with the volume of fluid (VOF) surface tracking method has been developed for a simplified liquid desiccant dehumidifier. The model has taken the effect of the velocity field on the heat and mass transfer process into consideration. The desiccant flow has been simulated according to the impacts of gravity, viscosity and surface tension. Meanwhile, the variable physical properties of the desiccant and air have been adopted in the model. Moreover, unlike previous models for liquid desiccant dehumidifiers, the penetration mass transfer theory has been employed to make it possible to observe the dynamic heat and mass transfer process of the dehumidifier. The model has been proved to be reliable as the simulation results show good agreement with those of other models. Parametric studies are also performed to investigate impacts of various boundary conditions. The simulation results allow us to predict the water vapor concentration field, temperature field, local gradients of water vapor concentration, local film thickness, and influence of mass transfer on the film surface waves of the dehumidifier. (C) 2013 Elsevier Ltd. All rights reserved.