A one-dimensional (1-D) anodic aluminum oxide (AAO) pore array horizontally aligned on a Si(100) substrate with a pore diameter of 50 nm was fabricated using optimized anodization parameters. The oxide barrier layer at the pore base was removed in a diluted KCl solution, which was negatively biased at 2.5-5 V. A single array of cobalt nanowires horizontally aligned on the substrate was successfully electrodeposited inside the pores of the 1-D AAO pore array template. The Co nanowire array was clearly observed by scanning electron microscopy, and magnetic hysteresis curves of the samples were measured before and after cobalt deposition. (c) 2008 The Electrochemical Society.