We report size-controllable syntheses of spherical coordination polymer particles using only K-2[Pt(CN)(4)], Zn(NO3)(2) center dot 6H(2)O, and water, and their conversion to Pt-ZnO composite and PtZn alloy. This method can control both the size and surface morphology of coordination polymer particles by changing the concentrations of the starting materials without any organic solvents, surfactants, and heating treatment. For example, the increasing of [Pt(CN)(4)](2-) concentration reduced the particle size and improved the smoothness of particle surface. Thermal treatment of the particles in oxidative atmosphere at 500 degrees C results in the formation of Pt-ZnO composite. Upon further treatment in reducing atmosphere at 400 degrees C, the composite was converted to PtZn alloy compound. After conversion to composite and alloy, the initial particle size and surface morphology were retained.