The crystallization of scale forming minerals is an important problem in a number of processes. Calcium sulfate dihydrate (CaSO4 center dot 2H(2)O, gypsum) is the most unwelcome deposit in the production of oil and gas, in water cooling systems and in hydrometallurgical processes. Additives have been used in these processes to prevent the formation and deposition of scaling salts. In this study, the effects of additives on the spontaneuos precipitation of CaSO4 center dot 2H(2)O were investigated in aqueous solutions at 30 degrees C. Conductive copolymers with different vinylphosphonic acid (VPA) contents were used as additives. The degree of inhibition of cystallization was measured as an increase in induction time and the reduction in crystallization rate. The crystallization reactions were interpreted in terms of the Langmuir adsorption isotherm. The cystals were characterized by scanning electron microscope (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The VPA content of the copolymer and the supersaturation of the solution were found to be effective parameters on CaSO4 center dot 2H(2)O crystallization.