The polyol method was employed for the first time to synthesize cuprous oxide nanowires using only a precursor of Cu(II) acetate monohydrate and diethylene glycol (DEG). With careful control of the reaction temperature (190 °C), the precursor concentration (0.01−0.1 mol/L), and the reaction time (6 h), we prepared Cu2O nanowires with a diameter of approximately 20 nm and a length up to 5 μm. The nanowires were characterized by SEM, TEM, XRD, and IR spectroscopy.