The results of experiments for obtaining granulated sodium tripolyphosphate with bulk density adjustable within 1 00-1 05 kg/dm(3) and expected content of STPP crystalline phases are presented The scope of experiments included the identification of factors with statistically significant impacts on the study object and the estimation of response surface Because of the application of the Plackett-Burman design, 15 input factors could be evaluated regarding their impact significance and insignificant factors could be eliminated Moreover, the Hartley design enabled the determination of a response surface based on the general regression equation in the form of a second degree polynomial with double interactions The input factor values, determined on the basis of the prediction profile and desirability function, were used to perform a series of experiments to achieve STPP expected bulk density within the range of 1 00-1 05 kg/dm(3)