Solar energy is a clean source of energy that is available in all regions of the world. Bahrain, where the present research was conducted, is rich in solar energy expressed as hours of sunshine which ranges between 13 h per day in the summer months to 10 h per day in the winter months. Water desalination by solar energy can be effectively achieved by using an electrodialysis process operated with photovoltaic cells. This method is attractive because electrodialysis requires a D.C. power supply as the driving force for removing the salt ions. This experimental work involved a small-scale commercial-type electrodialysis stack powered by photovoltaic cells. The stack consisted of 24 cell pairs, arranged in four hydraulic stages and two electrical stages. The feed water was fed from two sources, the first being sodium chloride solutions prepared in the laboratory and the second was groundwater of medium salinity. The experiments were done at temperatures ranging from 10 to 40 degreesC and product flow rates ranging fro 50 to 300 gallons/day. Increasing the flow rate resulted in lower product quality given terms of percent salt removal. Increasing the temperature generally resulted in better product quality. (C) 2003 Elsevier Science Ltd. All rights reserved.