The aim of this research was to examine the applicability of the conductometric method for measuring the concentration of potassium sulfate solution during crystallization by cooling. In the first part of the research, calibration curves, i.e. the dependence of the conductivity, , on the concentration of potassium sulfate solutions, c, in the range from 0.40 to 0.72 mol dm -3 at given temperatures, T, in the range from 35 to 15 °C were created. From the results, it was observed that the conductivity increases with the increase in the concentration and temperature of the potassium sulfate solution, and in order to facilitate the application of this method, a correlation equation was developed to express the dependence of the conductivity on the concentration and temperature of the form:  = K · c a ∙ T d . The exponents of the equation were estimated using the so-called modified linear regression, which first determined the value of the exponent a from the dependence  = k 1 · c a (log  = a log c + log k 1 ) at constant temperature values, in the given temperature range, and then defined the value of the exponent d from the relation   = k 2 · T d at constant concentration values in the given concentration range. After determining the value of the exponents aid, the value of the proportionality constant K was determined by equating the correlation equation with the experimentally measured conductivity values, which resulted in the final form of the equation:  = 35.57 · c 0.8475 ∙ T 0.453 which indicates that the conductivity depends more on the concentration rather than temperature. In order to determine the accuracy and precision of the applied method, the derived equation was used to calculate the known concentrations of solutions based on the measured values of conductivity and temperature. These tests showed that the applied conductometric method with the use of the correlation equation is moderately reliable. In the second part of the research, the conductometric method with the application of the correlation equation, was used to determine the concentration of the potassium sulfate solution during its recrystallization from the mother solution saturated at 30 °C by cooling to 15 °C. From the obtained concentration curve, the region of the metastable zone and the nucleation temperature were estimated and those values slightly deviate from those determined visually.