Mn 2+, Co 2+, or Ni 2+monodoped CdS (or ZnS) and Mn 2+-Co 2+-Ni 2+tridoped CdS (or ZnS) have been successfully synthesized by novel one-step thermolysis method using thiourea as a sulphur source. The synthesized nanomaterials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). It is found that the average diameter and morphology of the synthesized samples varied with the nature of dopant ion. The successful doping of Mn 2+-Co 2+-Ni 2+tridoped ions into the host CdS (or ZnS) was proved by the EDX spectra. The luminescence of CdS is only enhanced when monodoped with Mn 2+whereas it is enhanced when ZnS is either monodoped with Mn 2+, Co 2+, or Ni 2+or tridoped with Mn 2+-Co 2+-Ni 2+. The synthesized samples could therefore offer opportunities for further fundamental research and technological applications.