Pure ZnO and Co-doped ZnO (Zn0.98Co0.02O) nano-powder have been synthesized by co-precipitation method. Detailed XRD analysis shows that prepared nanocrystalline samples have single phase, wurtzite structure. Relative increment in (002) Bragg peak has been observed due to one dimensional growth in Co ions doped ZnO. The SAED pattern and TEM images confirm the single phase, wurtzite structure and nano-ampoule shape of Co-doped ZnO. In UV-vis measurements, the absorption edge is blue shifted with Co-doping in ZnO lattice. Tuned band gap of ZnO with Co-doping offers its potential application in solar cells. (C) 2016 Elsevier B.V. All rights reserved.