The effect of yttrium content and heat-treatment processes on the room temperature resistivity and grain size of polycrystalline (Ba-0.8-xSr(0.2))YxTO3 ceramics has been systematically studied using response surface method. The yttrium content, sintering temperature and cooling rate were taken as experimental factors. The modeling equations for the room temperature resistivity and grain size were obtained by using three experimental factors and measured values of the room temperature resistivity and grain size. The yttrium content has larger effect than other experimental factors on the room temperature resistivity and grain size. The validity of polynomial equations was confirmed by comparing the predicted values with those obtained from additional experiments.