Abstract. The adsorption of Fe(II) from aqueous solutions by acid modified jackfruit wood sawdust biosorbent was investigated in a batch adsorption system. The experiment conducted at room temperature and pH 5 resulted adsorption behaviour of chemical modified Jackfruit wood sawdust biosorbent. The removal of Fe(II) has been found to be the function of initial Fe(II) concentration, acid type and acid concentration. The best removal was at low Fe(II) initial concentration, the higher initial concentration resulted on lower adsorption. Untreated jackfruit wood sawdust has the highest adsorption efficiency, followed by acetic acid, citric acid and tartaric acid modified jackfruit wood sawdust. The maximum uptake capacity of Fe (II) ion was 1.05 mg/g by untreated jackfruit wood sawdust.