A theoretical model is developed to simulate the heat and mass transfer processes in a cross flow dehumidifier/regenerator using liquid desiccant. The model depends on NTU as input parameter, and NTU can be correlated based on the corresponding experimental data. The model is able to predict the air and desiccant parameters inside the dehumidifier/regenerator, as well as the outlet parameters, with known inlet parameters. The calculated results are compared with the experimental findings. For the total 284 groups of dehumidification experimental data with different module sizes, the average absolute discrepancies for enthalpy effectiveness and moisture effectiveness are 7.9% and 8.5%, respectively. For the 82 groups of regeneration experimental results, the average discrepancies for enthalpy and moisture effectiveness are 5.8% and 6.9%, respectively. The distributions of desiccant outlet temperatures are measured during both the dehumidification and regeneration processes, and the temperatures predicted by the theoretical model agree well with the experimental results. (c) 2006 Elsevier Ltd. All rights reserved.