Nanocrystalline ZnO powders have been synthesized by using zinc acetate dihydrate and polyvinylpyrrolidone (PVP) as starting materials. The calcined powders in air at 600 o C for 1 hour have been characterized by XRD, indicating the wurtzite or hexagonal structure with crystallite size of about 45 nm. The TEM image gives the grain size of about 100 nm in diameter at 3x10 -4 M PVP. The morphology of ZnO powders has been changed from platelet-like to rod shape with increase in PVP concentrations. The calcined ZnO powders have exhibited the direct optical band gap of about 3.222-3.237 eV and its photoluminescence has performed the UV emission peak at about 390 nm with small blue shift due to smaller grain size at higher PVP concentrations.