There is growing interest in reclaiming waste materials from industries such as metallurgical slags, fly ash and agricultural wastes in a resource-limited world. A large amount of steel slag is produced as waste material from steel industries. This study focused on natural organic matter (NOM) removal using steel slag as a low-cost adsorbent/catalyst. The aim of this study was to investigate the potential use of steel slag to remove NOM in waters with high specific UV absorbance (SUVA254) value. The effects of steel slag particles size and dosages of slag and hydrogen peroxide on NOM removals were determined. UV absorbing NOM fractions were preferentially removed by the steel slag. Maximum UV absorbance and dissolved organic carbon (DOC) reduction after adsorption were 83% and 54%, respectively. In addition to adsorptive properties, iron oxides on steel slag surfaces significantly catalyses hydrogen peroxide decomposition. As a result of formation of strong oxidants after hydrogen peroxide decomposition, NOM removal increased. The results showed that steel slag can be used as adsorbent and catalyst for removal of NOM in high SUVA value waters. Besides, steel slag may be effective for controlling the formation of disinfection by-products (DBPs) in drinking water treatment due to the removal of NOM fractions with high UV absorbance values.