Silica particles coated with proton conductive layers composed of block copolymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization with particles (PwP). The experimental results verified the successful formation of poly(acrylic acid)-b-polystyrene-coated silica particles via RAFT PwP. The new particles can be applied in novel filler in electrolyte membranes for polymer electrolyte fuel cells.