In this paper, an experimental and theoretical discussion of a humidification and dehumidification (HDH) solar desalination system is presented. The influence of the surface area of spherical plastic balls in humidifier packing is examined at different flow rates of both hot brine and cold water, and the temperature of the cooling water. The results demonstrate that gain output ratio (GOR) and productivity are augmented with increasing the ball packing surface area from 1.09 to 1.4 m2, and with increasing the flow rates of hot/cold streams. While the cold-water inlet temperature has a negative effect.