4-(3-methyl-1-imidazolio)-1-butanesulphonic acid triflate (BSMIMOTF)-Nafion film is introduced as a novel catalyst support. Nafion is used as the conductive membrane for BSMIMOTF immobilisation. A uniform distribution of spherical platinum nanoparticles (PtNPs) 10-30 nm in diameter can be electrochemically deposited on the membranous BSMIMOTF-Nafion matrix. Compared with the PtNPs on a bare and Nafionmodified electrode, the proposed sulphonyl-terminated ionic liquid (IL)-Nafion stabilised PtNPs exhibit higher electrocatalytic activity and better stability towards the electro-oxidation of methanol. The IL-Nafion film as a new catalyst support has great potential application in direct-methanol fuel cells.