<p>Herein, the successive ionic layer adsorption and reaction method was used to synthesize cadmium oxide (CdO) with excellent optical and electrical properties at room temperature. Four thin films of varying thicknesses were grown and analyzed for their optical, structural, and electrical properties. X-ray diffraction (XRD), scanning electron microscopy-coupled energy-dispersive X-ray spectroscopy, and atomic force microscopy were used to examine the structural properties of the CdO thin films, while ultraviolet–visible spectroscopy assessed their optical properties. The two-point probe method was used to investigate the electrical properties of these films. The results indicated that increasing the CdO film thickness led to increased peak intensities in their XRD patterns, indicating an improvement in the crystal structure. In addition, the energy bandgap of these films increased from 1.97 to 2.6&#xa0;eV with increasing film thickness.</p>