A desalination system has been designed for converting brackish water into potable water utilizing ocean thermal gradient. The desalination plant evaporates the water by flash and surface evaporation and subsequently the vapour is condensed to get potable water. An experimental plant with a capacity of 20 lph was designed for a typical ocean thermal gradient. The designed operating conditions of the plant are evaporator temperature, 30 degrees C and condenser temperature, 10 degrees C. Experimental performance of the system was evaluated by varying the condenser and evaporator temperatures and chamber vacuum pressure.