In this work, a natural zeolite previously conditioned with NaCl solution was modified with different hexadecyltrimethylammonium-bromide concentrations for methamidophos removal. All materials were characterized by diverse analytical techniques. Methamidophos adsorption behavior was studied by using batch experiments. Main structural and textural differences of surfactant-modified zeolitic materials were correlated with methamidophos adsorption capacity. Methamidophos adsorption was enhanced when zeolitic materials were modified with HDTMA and, more significantly, when a 25 mmol/L surfactant concentration was used, achieving a maximum adsorption capacity of 1.13 mg/g due to its pore surface modification. In this way, methamidophos adsorption present in aqueous solution was improved.