[en] CdS@Mn(OH)₂ nanocomposites were prepared using a novel aqueous seed-mediated growth approach. The CdS@Mn(OH)₂ nanocomposites were characterized by means of X-Ray Diffraction, Energy-Dispersive X-ray analysis, Transmission Electron Microscopy and FT-IR analysis. The MAA-CdS and CdS@Mn(OH)₂ composite nanoparticles average size was about 3.2 nm and 5.1 nm, respectively. The refluxing time and the concentration effect of Mn²⁺ on the nanocomposite optical properties were studied using UV-visible absorption and photoluminescence techniques. The CdS@Mn(OH)₂ composite nanoparticles emission peak was shifted from 508 nm to 536 nm, which indicates the successful doping of Mn²⁺ into CdS nanoparticles. An efficient energy transfer process was observed from the bare MAA-CdS nanoparticles to the CdS@Mn(OH)₂ nanocomposite.