The effect of concentration of saccharose (30-80 g/L) and ammonium sulfate (0.2-1.0 g/L) in the medium on the synthesis of pullulan in batch culture of A. piillulans A.p.-3 was studied. Several combinations of concentration of these compounds were used and the kinetics of biosynthesis was studied during 96 h of cultivation. Based on the mathematical model derived, it was assessed that the optimum concentrations of saccharose and ammonium sulfate in the medium were 60 g/L and 0.72 g/L, respectively. The yield of pullulan in the medium with the optimal concentrations of saccharose and ammonium sulfate was 9.9 g/L after 96 h of cultivation.