Carbon black nanoparticle grafted with poly(N-isopropylacrylamide) (CB-g-PNIPAAm) was synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP). The temperature-responsive behavior of CB-g-PNIPAAm was proved by temperature-variable H-1 NMR. A temperature-dependent conductive composite was prepared by blending CB-g-PNIPAAm with epoxy resin. The relationship between temperature and resistivity of the composite was studied: the composite exhibited a negative temperature coefficient (NTC) phenomenon. Possible mechanism for the NTC phenomenon was suggested. The results showed that resultant composites can be used in intelligent temperature-switching. (C) 2008 Wiley Periodicals, Inc.