CdO (ZnO) nanoparticles (NPs) are known for their high surface area and quantum confinement. In this paper, there is a discussion on the synthesis of pure, Fe-doped, and glucose-capped CdO (ZnO) NPs by the precipitation method. Their structural and optical properties were studied with the help of XRD, SEM, FTIR, and UV–Vis spectrometry. A single phase with hexagonal (cubic) structures was obtained from their XRD patterns. The pure, Fe-doped, and glucose-capped CdO (ZnO) had crystallite sizes of 15.89, 15.33, and 11.19 nm (1.66, 1.01, and 1.78 nm) obtained from XRD. Their FTIR data agreed well with their XRD data. The particles were spherical. The energy bandgap of CdO (ZnO) was 3.78, 3.65, and 3.63 eV (3.82, 3.80, and 3.63 eV) for pure, Fe-doped, and capped samples, respectively, obtained with the help of photoluminescence. The inhibition zones are found to be 11, 7, and 13 (12, 10, and 7), respectively.