|| Total organic carbon (TOC) including nitrogen-based organic compounds still remain in the ultrapure water (UPW). This TOC hinders the ultrafine photolithography process. In this work, we have developed an effective ion exchange material to reduce TOC in UPW. The ion exchange material is a micro-composite composed of magnetic (Fe3O4) nanoparticles (MNPs) and microbeads of cation exchange resin (CIER). MNPs were surface-modified with vinyl groups and then physicochemically adsorbed on the microbeads of CIER. Surface-modified MNPs and micro-composite were analyzed by XPS, SEM, TEM, FT-IR and TGA. A TOC reduction test using a micro-composite was also conducted.