The constructions and the characteristics of a transformer- driven stroboscopic x-ray generator (SX-T98) are described. This generator is primarily designed in order to increase the maximum photon energy of the pulsed x-rays and is composed of the following essential components: a thyratron pulser, a high-voltage transformer having a ferrite core with a maximum output voltage of 300 kV, a sequence controller, a DC power supply for the hot cathode (filament), and an x-ray tube. The main condenser of 24 nF in the pulser is charged up to 14 kV, and the electric charges in the condenser are discharged repetitively to the primary coil of the transformer. Because the high-voltage pulses from the secondary coil are then applied to the x-ray tube, repetitive harder x-rays are produced. The x-ray tube is of a triode having a hot-cathode which is primarily driven at the temperature-limited current region In this triode, because the grid is connected to the cathode, this tube is driven as a diode. The tube voltage roughly increased in proportion to the charging voltage, and the maximum value was about 300 kV. Thus, the maximum photon energy had a value of about 300 keV. The tube current was primarily determined by the filament temperature and had values of less than 2 A. The x-ray output displayed plural pulses, and the pulse width of the first pulse was about 300 ns. The maximum repetition rate was about 1 kHz, and the dimension of the x-ray source had values of 3.5 X 3.5 mm.