In this study, thermal performance of the salt gradient solar pond (SGSP), which of density gradient is artificially with sodium carbonate solution, was tested under Karabuk prevailing weather conditions in Turkey. A small-scale prismatic glass tank was constructed with an area of 0.45 x 0.20 m(2) and a depth of 0.25 m as solar pond. A series of experiments with four different density levels were conducted in July-August 2004. The variations of the temperature and density profiles were observed for each of experiment for a week. It was found that the maximum temperature difference between the bottom and surface of the pond is 21 degrees C and maximum temperature in the lower convective zone (LCZ) has been measured as 49 degrees C at the first experiment. The efficiency of the pond was evaluated 13.33% weekly mean radiation intensity of 524 W m(-2) for the first experiment. Copyright (c) 2006 John Wiley & Sons, Ltd.