Abstract: Hollow carbon nanospheres (HCNs) were synthesized by carbonizing fine core/shell particles of polymethylmethacrylate (PMMA)/polyacrylonitrile (PAN). The PMMA/PAN core/shell particles were prepared using twostage soapless emulsion polymerization. PMMA spheres with a diameter of approximately 200nm were first synthesised by batch mode polymerization and then a PAN shell with a thickness of approximately 30nm was polymerized on the surface of PMMA spheres by dropwise addition of acrylonitrile monomer. After freeze drying, PMMA/PAN composite particles were stabilized in air at 250℃ and then carbonized in nitrogen at 1000℃. Transmission electron microscopy of the final sample showed that all PMMA cores turned into pores and all PAN shells developed into carbon shells. The PMMA/PAN composite particles were converted to HCNs with some adhering with each other and some breaking of the carbon shells.