Vertically　aligned　zinc　oxide　(ZnO)　nanorods　(NRs)　were　hydrothermally　synthesized　from　0.1　M　zinc　acetate　solution　on　ZnO-seeded　Si(100)　substrates.　ZnO　NRs　with　copper　addition　were　also　synthesized　by　introducing　copper　acetate　into　the　zinc　acetate　solution　to　investigate　the　effects　of　copper　addition　on　the　growth　and　resistive　switching　of　the　ZnO　nanorods.　The　ZnO　NRs　had　hexagonal　wurtzite　structure　with　preferential　c-axis　orientation.　Copper　was　mainly　present　as　copper　oxide　(CuO)　secondary　phase　which　produces　many　visible　defects,　and　the　lattice　fringes　of　the　ZnO　NRs　are　thereby　damaged.　Copper　addition　quenches　the　ultraviolet　emission　of　the　ZnO　NRs　but　enhances　their　green　emission.　Additionally,　copper　addition　shifts　the　Zn　2p　and　O　1s　peaks　of　the　x-ray　photoelectron　spectra　towards　lower　binding　energy,　which　may　result　from　an　increase　of　oxygen　vacancies.　ZnO　NRs　with　and　without　copper　addition　exhibit　reversible　bipolar　resistive　switching.　The　copper　addition　shrinks　the　deviations　of　programming　voltages,　with　a　decrease　in　the　minimal　set　voltage　and　an　increase　in　the　minimal　reset　voltage,　which　can　probably　be　attributed　to　the　introduced　oxygen　vacancies　and　the　copper-related　defects.　©　2014　TMS.