Effect of three different cooling rates is investigated on crystallization kinetics of potassium chloride. The gravimeric method is used to measure the concentration of potassium chloride in the liquid phase as a function of time. The method proved to be simple and accurate. A non-linear optimization method is applied to estimate the growth and nucleation rate parameters from unseeded batch cooling crystallization experiments. The effect of the cooling rate profiles on the parameters and on the final mean particle size is discussed.