A positive temperature coefficient (PTC) composition that has improved thermal conductivity and that includes a thermoplastic polymer, carbon black and graphite. The compositions offer improved thermal conductivity and/or rheology of the PTC composition as compared to compositions that do not include graphite, or that use smaller graphite particles. The compositions may also include one or more additives. The PTC compositions of the present invention offer improved thermal conductivity at most any temperature and permit PTC materials to be designed that can be tailored to operate at different temperatures based upon the thermoplastic polymer used.