A Flash X-ray diode has been designed and developed for generation of single shot, nanosecond duration x-rays from KALI-5000 Pulse Power System (0.8-1 MV, 40 kA, 100 ns). The typical electron beam parameter was 500 kV, 8 kA, 100 ns, with a few hundreds of A/cm current density. The spot size for different diode configurations varied from 4 mm to 2 mm. X-ray radiograph of various metal objects were taken on X-ray films. The diode voltage and current waveforms were analyzed with the space-charge limited flow model. The anode and cathode plasma expansion velocities were calculated using the perveance data and varies from 2.5-3.3 cm/μs. Time integrated x-ray dose was measured using pen dosemeter and the on-axis dose was 10 mR at 1m distance from the window. The radiograph of stainless steel objects shows good resolution. © 2011 IEEE.