<p>In this study, manganese (Mn)-doped cadmium oxide (CdO) nanoparticles were synthesized using a co-precipitation method to investigate the influence of Mn incorporation on their structural, optical, and morphological properties. CdO, a well-known n-type semiconductor with a cubic crystal structure, exhibits promising potential in optoelectronic and photocatalytic applications. However, its performance can be further enhanced through doping with transition metals. Characterization of the Mn-doped CdO nanoparticles was carried out using UV, FTIR, XRD, PL, SEM, EDX and TEM. UV–Vis analysis revealed a blue shift in the absorption edge with Mn doping, indicating an increase in bandgap energy due to the Burstein-Moss effect and quantum confinement. XRD patterns confirmed the retention of the cubic phase of CdO, with slight peak shifts suggesting successful Mn incorporation and lattice distortion. FTIR spectra exhibited characteristic Cd–O stretching vibrations, along with bands corresponding to Mn–O and adsorbed surface species. SEM and TEM analyses revealed a nanocrystalline morphology with reduced particle size upon Mn doping, while EDX confirmed the elemental composition and successful substitution of Mn into the CdO lattice. The results demonstrate that Mn doping significantly modifies the physicochemical properties of CdO nanoparticles, making them suitable for potential applications in photocatalysis, gas sensing, and spintronics. This work contributes to the growing field of doped metal oxide nanomaterials and their functional enhancements through controlled doping strategies.</p>