The synthesis of hollow, cross-linked polymer particles ('capsules') via Pickering miniemulsion polymerization using graphene oxide (GO) nanosheets as sole surfactant is reported. The influence of monomer, cross-linker and initiator type was studied, in addition to hydrophobe loading and initiator concentration. The desired hollow capsule morphology was shown to be strongly dependent on the choice of cross-linker; an aromatic crosslinker (divinylbenzene) consistently yielded hollow structures as determined by transmission electron microscopy, whereas ethylene glycol dimethacrylate typically resulted in polymer particles with a solid core. The use of an aromatic monomer with high propagation rate coefficient (benzyl methacrylate) and a strongly oil-soluble initiator, lauroyl peroxide, resulted in capsule synthesis with very high conversion (>85%) after 6 h. Surface area and pore analysis of the capsules established that while the capsules possessed a hollow interior, the shell was essentially nonporous. The potential of these materials towards novel nanocarbon-based materials was demonstrated via the preservation of colloidal stability and particle morphology after chemical reduction of GO, in addition to successful encapsulation of hydrophobic nanoparticles within the capsule core. (C) 2015 Elsevier Ltd. All rights reserved.