Sodium bentonite was subjected to the effect of two new homologue series of chlorides (alcoxymethyl) dimethyloctyloamonium chlorides and 3-alcoxymethyl-1-octylimidazole chlorides with the hydrophobic substituents of the same length. Morphology of the obtained modified bentonite was studied under scanning electron microscope [SEM] and the degree of adsorption of the ammonium salts was determined by two-phase titration. The results allowed an assessment of the influence of the length of the hydrophobic substituents and the site of the quaternary nitrogen atom on the adsorption of chlorides.