On a Cu (001) surface vicinal to a [100] direction, single rows of square patches c(2 x 2)N in the direction of [010] can be formed on narrow terraces. We deposited Co on the vicinal Cu(001)-c(2 x 2)N surface, and investigated the magnetic properties of the Co nano-dot array at a temperature range of between 90 and 300 K, using an in situ surface magneto optical Kerr effect. When an average of 1.4 ML of Co was deposited on the surface, rectangular shape hysteresis loops of in-plane magnetization, parallel to the direction of [010], were observed below 130 K. This indicates that the easy magnetization axis is along the step edge. (C) 2004 Elsevier B.V. All rights reserved.