The precursor of nanopowder ZnO was synthesized by direct precipitation method and compacted to bulk samples. The bulk ZnO was annealed by furnace at temperature range of 400–650 °C in air for 30 min. The crystallography of precursor and bulk powder of ZnO was analyzed by the X-ray diffraction (XRD) and scanning electron microscopy (SEM) and obtained the hexagonal crystal structure, mean lattice parameters of a = b = 3.2478 Å and c = 5.2037 Å and unit cell volume of 47.53 Å3. The particle size was investigated by SEM and evaluated by XRD results about 76.28 nm and bulk density of 3494.14 kg m−3. The thermopower was measured by steady state method and obtained highest value of −92.99 μV K−1 at room temperature for annealing temperature of 550 °C.