We report that two 10‐Å [Cd20S13(SPh)22]−8clusters may be fused together to form a 13‐Å CdS cluster, which shows a sharp absorption peak at 370 nm and a luminescence peak at 390 nm. This is supported by the concentration dependence of the absorption spectra, the luminescence‐excitation spectra, the capillary zone electrophoresis separation, the electrochemical measurement, and the powder X‐ray data. This cluster fusion process occurs naturally in solution at high concentrations of [Cd20S13(SPh)22]−8. It can also be induced electrochemically by a two‐electron oxidation process. We also show that capillary zone electrophoresis and electrochemical synthesis are two useful new techniques for obtaining monodisperse CdS clusters. Their potentials and limitations are discussed.