Cobalt (Co) is one of the most important heavy metals found in the wastewaters. Some metals such as Co in wastewater from chemical-based industries can have toxic or harmful effects on life forms. Hence, removal of toxic metals in wastewater causing environmental hazards has a great importance. In this work removal of Co(II) ions with adsorption from aqueous solutions by natural pumice has been investigated in a batch system. Response Surface Methodology (RSM) including the central composite design (CCD) was successfully applied to develop a response surface and optimize the medium conditions affecting significantly the adsorption such as pH, initial Co(II) concentration (Co) and temperature (T, degrees C). In CCD, optimum conditions were determined by the model equation obtained from the quadratic model fitting the experimental results. These optimum conditions were found to be 7.79, 69.84 mg/L and 20 degrees C for pH, Co and temperature, respectively. At these optimum conditions, the adsorption capacity and adsorption yield were calculated as 2.816 mg/g and 40.32%, respectively. Then, the data obtained by the program were confirmed by experiments.