A practical oxide thermoelectric module consisting of 12 pairs of p-NaCo2O4 and nanostructured n-ZnO sintered materials was successfully fabricated by using a diffusion welding technique. By applying a nanostructure using a void forming agency (VFA), the electrical conductivity of the n-ZnO sintered materials were drastically enhanced, leading that the power factor of the materials were dramatically improved. It is revealed that the oxide module can be operated up to 930 K on the hot side temperature. A maximum power output of 52.5 mW was achieved at the temperature condition of T H/TL = 934/479 K, where TH and TL are temperatures at the hot and cold sides of the module, respectively. The details of the power generation characteristics of the present oxide module will be presented and the performance will be discussed with those of our previous and other oxide modules.