We report herewith the synthesis of hollow Pt nanospheres by using bis(p-sulfonatophenyl)phenylphosphine to selectively remove the Ag cores of Ag-Pt core-shell nanoparticles. Core-shell Ag-Pt nanoparticles were first obtained by the successive reduction method with a discontinuous Pt shell to allow the BSPP passage. Transmission electron microscopy imaging of the core-shell Ag-Pt nanoparticles before and after BSPP dissolution showed little changes in the particle size, indicating that the removal of the Ag cores had occurred isomorphously. The hollow Pt nanospheres, together with the predecessor Ag-Pt core-shell particles of the same size, were transferred from water to toluene and surface modified by dodecylamine in toluene. This allows the catalytic activities of solid and hollow Pt particles in room temperature methanol oxidation reaction to be compared under conditions of identical particle size and the same surface environment. The measured higher specific activity of the Pt hollow nanospheres could then be attributed unambiguously to the larger specific surface area prevalent in the porous hollow structure.