Transparent conducting oxide CdO has a wide range of applications in optoelectronics. We present the results of electronic and optical properties of pure and transition metal ions Sc, Y and Ti-doped CdO. The electronic structure is calculated within the full-potential linearized augmented plane wave (LAPW) + local orbitals (lo). The calculated band gap for pure CdO is 0.51 eV and changes significantly with doping. The calculated bandgap for Sc-doped CdO (CSO) is 2.67 eV, for Y-doped CdO (CYO) is 2.93 eV, and for Ti-doped CdO (CTO) is 2.53 eV. The effect of doping is clearly seen in the optical absorption profiles as well as in the enhanced electrical conductivities. Due to the widened optical transparency window, doped TCO has nearly 75-80% transmittance in the optical region. There is possibility of greater multiple direct and indirect interband transitions due to availability of more states compared to pure CdO.