The interaction of dextrin with colloidal ZnS has been investigated through adsorption studies and FT-IR spectroscopy in the 4000-400 cm(-1) range. The adsorption capacity is estimated to be around 1 mg/m(2). Maximum adsorption is found to be constant below pH similar to 7 and to increase with pH at least up to pH 11. Eighty percent of maximum adsorption is achieved within 3 min after addition of the dextrin. Based upon FT-IR studies and titration data, an adsorption mechanism is proposed.