This　paper　describes　experimental　studies　of　the　dependence　of　the　X-ray　intensity　on　the　anode　material　in　nanosecond　high-voltage　discharges.　The　discharges　were　generated　by　two　nanosecond-pulse　generators　in　atmospheric　air　with　a　highly　inhomogeneous　electric　field　by　a　tube-plate　gap.　The　output　pulse　of　the　first　generator　(repetitive　pulse　generator)　has　a　rise　time　of　about　15　ns　and　a　full　width　at　half　maximum　of　30-40　ns.　The　output　of　the　second　generator　(single　pulse　generator)　has　a　rise　time　of　about　0.3　ns　and　a　full　width　at　half　maximum　of　1　ns.　The　electrical　characteristics　and　the　X-ray　emission　of　nanosecond-pulse　discharge　in　atmospheric　air　are　studied　by　the　measurement　of　voltage-current　waveforms,　discharge　images,　X-ray　count　and　dose.　Our　experimental　results　showed　that　the　anode　material　rarely　affects　electrical　characteristics,　but　it　can　significantly　affect　the　X-ray　density.　Comparing　the　density　of　X-rays,　it　was　shown　that　the　highest　x-rays　density　occurred　in　the　diffuse　discharge　in　repetitive　pulse　mode,　then　the　spark　discharge　with　a　small　air　gap,　and　then　the　corona　discharge　with　a　large　air　gap,　in　which　the　X-ray　density　was　the　lowest.　Therefore,　it　could　be　confirmed　that　the　bremsstrahlung　at　the　anode　contributes　to　the　X-ray　emission　from　nanosecond-pulse　discharges.　(C)　2012　American　Institute　of　Physics.　[http://dx.doi.org/10.1063/1.4773439]