Nickel oxide films were deposited with Ni(C5H5)(2)(bis-cyclopentadienyl nickel)/O-2 at various temperatures and O-2 flow rates. Gas phase reaction of Ni(C5H5)(2)/O-2 was observed above the temperature of 300 degreesC and a peak from CO2, the product of the Ni(C5H5)(2) oxidation, was observed. Pure oxide films were not obtained but a mixed phase of nickel, NiO and Ni2O3 was observed and the amount of each phase in the film depended on the deposition condition. Films deposited at a high deposition temperature region (> 275 degreesC) had a high nickel content, and NiO(111) preferred crystal orientation. Films deposited at a low deposition temperature region (< 275 degreesC) had low nickel content and NiO(200) preferred orientation.