Cupricoxide(CuO)isconsideredtobeapromisingmaterialforphotovoltaicapplications.Inthispaper,p-CuO/n-Sijunctionsolarcellswereobtainedbythermaloxidationofmetalliccopperfilmsdepositedonn-Sisubstratesat400℃for5h.X-raydiffractionpatternsshowthattheas-preparedfilmsareCuOwithmonocliniccrystallinestructure.HalleffectmeasurementresultsshowthatCuOfilmsarep-typeconduction.Adirectband-gapof~1.57eVfortheCuOfilmisdeducedfromUV-VisAbsorbancespectra.SolarcellsofCu/p-CuO/n-Si/AlstructureshowthatitsphotovoltaicbehaviorhasamuchwiderspectrumresponsewidthcomparedwiththatofSisolarcells.Inaddition,thephotocurrentofCuO/n-SijunctionisinvestigatedasafunctionofCuOfilmthickness,anditisfoundthatthecriticalthicknessforCuOonSiisabout250nm.