Cuprous oxide (Cu₂O) nanowires were prepared by electrodeposition into a porous alumina template. To deposit the Cu₂O nanowires defect-free into the alumina membrane, a cathodic current density of -0.5 ㎃/㎠ was constantly applied in a copper sulfate electrolyte in the presence of lactic acid. Top-view and cross-sectional observations by TEM and SEM showed homogeneous filling of the Cu₂O nanowires in the 100- and 200-㎚ alumina pores. The length of the Cu₂O nanowires was 4 ㎛. EDS data indicated pure Cu₂O and XRD analysis showed preferential growth of Cu₂O (200) and (111) nanowires in the absence of Cu metal and CuO.