The evaluation of each 10 kV, 400 kA Si SGTO included a visual inspection and high-potting of each component module prior to pulsing. The complete unit was then switched in a low inductance RLC circuit to test voltage and current capabilities and maximize dI/dt. Devices were switched as many as 70 times without failure. Voltage sharing between the layers was within ± 2%, and current sharing between the modules was ± 5% of ideal sharing. The peak rate of current rise attained was 40 kA/μs, and the 50% pulse width of the current was 26 μs. The peak power switched was 1.06 GW, and the action of the forward current pulse reached 6.4 MA2s. This report includes details on the methods for evaluating the 400 kA SGTO, challenges faced and peak performance of the devices under single shot pulsing conditions.