Poly(styrene-co-methacrylic acid) P(St-co-MAA) microspheres with a monodisperse size distribution were prepared by emulsifier-free emulsion copolymerization of St and MAA. The effects of MAA. content on the polymerization rate and the content of MAA in the copolymer were investigated by gravimetrical and IR methods, respectively. The results of XPS measurement indicated the presence of a carboxyl functional group. By chemical metal deposition, nickel or palladium particles were formed and deposited on the surface of P(St-co-MAA) microspheres to form P(St-co-MAA)Ni or P(St-co-MAA)Pd composite particles. XRD measurement and TEM observation confirmed that nickel and palladium metal particles in a small size (20-40 nm) were distributed on surface of the copolymer microspheres. (C) 2000 John Wiley & Sons, Inc.