In the present study, adsorption of beta-carotene from soy oil with acid-activated rice hull ashes was conducted under vacuum. Concentrations of beta-carotene in the oils before and after adsorption were measured by a UV-vis spectrophotometer. The adsorption rate was found to be increased by increasing the ratio of activated rice hull ash/soy oil or bleaching temperature and by decreasing the particle size of activated rice hull ash. Furthermore, an adsorption rate expression has been determined.