A new and low cost acid hydrolyzed charred sawdust as an adsorbent has been used for the purification of edible oils. The maximum colouring matter adsorbed Gamma(p)(m) (mg/m(2)) for different oils on sawdust has been calculated. The change in free energy -DeltaG x 10(-1) (kJ/mol) due to adsorption of colouring matter from the bulk to the interface of the sawdust has been calculated. From our result it has been found that the maximum adsorption has been comparable to the change in free energy. The thermodynamic parameters such as the activation energy, enthalpy, and entropy are presented. The negative value of AS indicates less disorder i.e. the crude oil contains more colourant and impurities before bleaching process and these are decreased during adsorption process because disorder is directly proportional with entropy. (C) 2003 Elsevier Ltd. All rights reserved.