CdS nanocrystals were prepared in chelate polymer microparticles, and characterizations of the CdS/polymer polymer hybrids were performed by absorption microspectroscopy, optical microscopy, and transmission electron microscope measurements. When CdS nanocrystals were prepared by the reaction of Cd2+-polymer beads with a diluted HS- solution, formation of CdS was confined to the surface layer of the host polymer particle with a layer-by-layer size distribution. A preparation of CdS in the presence of NaCl (0.5 M) gave CdS with a smaller mean diameter, as compared to a sample synthesized without NaCl. The addition of NaCl also leads to a change in dispersion properties of CdS as well as in the time profile of CdS formation; the initial rate of CdS nanocrystal formation was accelerated by the addition of NaCl. The CdS nanocrystal formation rate was proportional to the square root of the reaction time, indicating that diffusion of HS- into the polymer particles controlled both optical and distribution characteristics of CdS. The results were explained in terms of a Donnan equilibrium model.