A solar still designed and built at Physics department Hacettepe University, Ankara, Turkey (39 degrees 57＇N), utilizes direct and reflected (from a reflector) solar radiation incident on a parallel double glass cover, to evaporate sea or brackish water. Water vapor purges from the evaporator and diffuses to an integrated condenser due to pressure difference exists as a result of the volume ratio and temperature difference between the evaporator and condenser. A theoretical analysis based on the energy balance for different components of the unit was performed. Graphical analysis were presented to show the variations of solar radiation, ambient temperature, basin water temperature, vapor temperature and other important temperatures at different locations in the solar still. The productivity was in good agreement with what obtained by other authors and the efficiency was increased from 48% to more than 70% when the condenser cover was cooled down.