The effects of graphene (G) and nanosilicon carbide (SiC) co-doping on the superconducting properties of MgB 2 were studied using bulk samples. SiC remains one of the best dopants which can significantly improve the high field performance, while graphene is emerging as a new dopant for MgB 2, which can improve the zero field critical current density (J c). The superconducting properties characterized by J c, the intergrain connectivity, and the critical fields were significantly improved by the use of both SiC and graphene as dopants. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.