Cuprous oxide ( Cu2O) films are prepared by simple thermal dry oxidation of sputtered Cu films at temperatures lower than 350° C. The relationship between growth rate of Cu2O film and oxidation temperature is formulated from both optical and Rutherford backscattering measurements, along with a similar relationship for the growth of cupric oxide (CuO). Electrical and structural properties of Cu2O films are measured by the van der Pauw and the X-ray diffraction methods respectively. It is found that stable Cu2O films can be obtained under suppression of CuO growth when Cu films are oxidized at about 300° C, and that the Hall mobility of such Cu2O films is relatively high and reaches to several tens cm2/Vs.