Decreasing the humidity ratio of ambient air can effectively prevent the frosting on the evaporator and improve the heat capacity of heat pump in winter. This paper conducts an experimental study and theoretical analysis on the heat and mass transfer performance of the cross-flow dehumidifier in a frost-free heat pump system. A mathematical model for predicting the heat and mass transfer performance in the dehumidifier is developed, and solved by finite difference method. Experimental study is carried out to analyze the influence of key parameters, including inlet air temperature, humidity ratio and flow rate, solution temperature, concentration and flow rate, on the coupled heat and mass transfer performance under low temperature and humidity ratio conditions. Based on the mathematical models and experimental results, the correlations of heat and mass transfer coefficients are proposed, and the deviations are within +/- 20%. Moreover, the effects of the inlet conditions of the liquid desiccant and air on the heat and mass transfer performance are compared with the experimental results reported in literature. (C) 2018 Elsevier Ltd. All rights reserved.