A solar desalination unit with humidification and dehumidification is presented. Experiments on the unit were conducted. It was found that the performance of the system was strongly dependent on the temperature of inlet salt water to the humidifier, the mass flow rate of salt water, and the mass flow rate of the process air. There existed an optimum rotation speed for the fan corresponding to an optimum mass flow rate of air with respect to both thermal efficiency and water production. The unit worked perfectly and the thermal efficiency was above 80%. Other low-grade heat resources such as waste heat can also be utilized to drive the desalination process. It was expected that the unit would be of great potential for use in desalination in arid areas and isolated islands.