Novel composites with nano-sized TiO₂ synthesized on the surface of bottom ash (NTB) were prepared for treatment of spent sulfidic caustic (SSC) wastewater. The efficiency of SSC wastewater treatment was compared and evaluated by using NTBs made with organic binder and inorganic binder, respectively. The treatment efficiency of NTB composite made with organic binder was higher than that of NTB composite made with inorganic binder. Although NBT composite made with inorganic binder had many pores on the surface, the white cement used as binder was excessively applied to the surface, and amount of coated nano-sized TiO₂ was decreased. The photocatalytic activity of nano-sized TiO₂ is more effective for SSC wastewater treatment than surface adsorption ability of surface pores.