Nanocrystalline transparent conducting CdO thin films were grown onto glass substrates by simple and economical sol-gel spin coating method. The structural, electrical, optical properties and morphological properties of the deposited films were investigated by X-ray diffractometry, dc resistivity measurements, UV-Vis transmission and absorption spectroscopy and scanning electron microscopy respectively. XRD studies revealed that CdO films are nanocrystalline in nature with cubic lattice. The variation of electrical resistivity with temperature conforms that films are semiconducting in nature. The optical characterization showed that nanocrystalline CdO film exhibits 3.42eV band gap energy which is attributed to quantum size effect.