Abstract: A process is provided for producing potassium sulfate by reacting ammonium sulfate and potassium chloride at a temperature of about 30 to 40° C. to produce a slurry containing K2SO4·NH4·2SO4 double salt, and reacting this double salt with an aqueous solution containing potassium chloride at a temperature of about 30° C. to produce a slurry containing potassium sulfate. The slurry containing potassium sulfate is subjected to a solids/liquid separation step to obtain potassium sulfate crystals having a size in the range of about 20 mesh to about 150 mesh.