Pd–graphene, a composite of Pd nanoparticles and exfoliated graphene, was used as a catalyst in organic reactions. In the Suzuki–Miyaura cross-coupling reaction, Pd–graphene showed high reusability without aggregation of Pd nanoparticles. The intermediates of the reaction in the liquid phase, Ph–Pd–Br and Ph–Pd–OH, were detected by ESI-MS.