Acid phosphatase activity, Zn (II) bioaccumulation and growth of R. delemar were investigated as a function of pH, temperature and initial Zn(II) ion concentration. Experimental design was performed by response surface method (RSM) and Box-Behnken design. The proposed mathematical models were evaluated by analysis of variance (ANNOVA) statistically method. The best fit for acid phosphatase activity was obtained by linear model, the Zn(II) bioaccumulation and microorganism growth were characterized by quadratic equations. The optimum conditions for acid phosphatase activity, Zn(II) bioaccumulation and growth of R. delemar were found to be pH 5,03, 31,82 degrees C and an initial Zn(II) ion concentration of 30,15 mg/L. At these conditions the maksimum acid phosphatase activity Zn(II) bioaccumulation and microorganism concentration were determined as 794,098 mmol / L-min, 17,62 mg / L and 3,2038 g / L respectively. To test sensivity and validity of the optimum conditions the validation experiments were performed.