This paper describes a relatively simple model for the preliminary design of an air dehumidification process occurring in a packed bed using liquid desiccant through dimensionless vapor pressure and temperature difference ratios. An expression is derived using the aforementioned ratios to predict the water condensation rate from the air to the desiccant solution in terms of known operating parameters. The model predictions were compared against a reliable set of experimental data available in the literature, with very good agreement. The effects of the cooling water inlet temperature and the desiccant-to-water heat exchanger effectiveness on the performance of the dehumidifier are also studied and the results are presented in this paper. (C) 2003 Elsevier Ltd. All rights reserved.