The effect of bath temperature on rotation of c-axis of hcp cobalt vis-a-vis the nanowire axis of 100 am diameter Co nanowires electrodeposited in polycarbonate membranes is studied. While the NWs deposited at 25 degrees C are of the polycrystalline hcp structure, the NWs deposited at 50 degrees C showed preferred orientation (PO) for (10 (1) over bar0) planes along the nanowire axis. In the nanowires deposited at 60 degrees C. the PO changes from (10 (1) over bar0) to (0002) along the nanowire axis. The changes in orientation are associated with the hydrogen co-deposition induced alterations in nucleation and growth mechanism at different temperatures. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.039212jes] All rights reserved.