A simulation model of thermal behaviour of a salt gradient solar pond is presented. The model is by far the most rigorous. It explicitly incorporates the effect of salinity and temperature on the thermophysical parameters (K, rho, C) of pond water and takes into account the heat and mass transfer processes at the pond surface. The model is used to investigate the temperature distribution and thermohydrodynamic stability of the pond water as a function of the day of the year of commencement of pond operation and heat withdrawal patterns. Annual variation of monthly averaged daily heat flux loss at the pond floor is studied to assess the thermal storage characteristics of the ground.