Highly uniform and monodisperse core-shell microspheres composed of a polystyrene (PS) core and a copper shell were prepared by dispersion polymerization of styrene followed by electroless copper plating. The formation of copper shell on PS surface was confirmed by FESEM, TEM, XRD and TGA. As a result, the plating bath composition had an important influence on the morphology of PS/Cu composites. The addition of Na(2)EDTA and La2O3 as a complexant and a stabilizer led to the formation of a more compact copper shell on PS surface. The formation mechanism was explored by the linear sweep voltammetry method, and the different morphology might mostly result from the various nucleation rates. Tailoring of shell thickness can be achieved through altering the loading of PS in the ECP bath. Conductivity of the PS/Cu composites with a shell thickness of 195 nm is up to 2.2x10(5) S/m. The PS/Cu composites may have great potential to be used as fillers of anisotropic conductive film for their uniform diameter, low density and good conductivity. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.045207jes] All rights reserved.