Clinoptilolites have a limitation in the adsorption of drug molecules due to their fixed pore structure. In this study, we modified the clinoptilolite with benzalkonium chloride. The modification was carried out by stirring 1 g of NaCl activated clinoptilolite with 100 mL of benzalkonium chloride solution with a concentration of 0.5, 1, 5, 10 and 15 % at room temperature for 24 h. After filtration and drying process, benzalkonium chloride modified clinoptilolite was stirred with 100 mL of 300 mg/L metformin hydrochloride solution at room temperature for 24 h. The result of sample characterization using FTIR spectrometer, X-ray diffractometer and N2 Sorption analyzer showed that clinoptilolite modification with benzalkonium chloride and the impregnation of metformin hydrochloride proceeded well. The optimal amount of metformin hydrochloride occurred in benzalkonium chloride 1 % modified clinoptilolite.