In this paper, the operational verification of the stacked transistor configuration is provided, focusing on the use of GaN transistors. The methodology is based on simulated and laboratory experiments. The stacked transistor configuration appears to be a promising solution to increase the voltage-blocking capability of GaN technology for high-voltage operations. Currently available GaN transistors are manufactured for 650 V of blocking voltage. Devices with a higher voltage-blocking capability are not currently available. Therefore, the stacked module was verified, while the main focus was on the driving circuit design, verification, and testing. For this purpose, two alternatives of GaN transistor technology have been compared. The main goal was to reach 800 V of blocking voltage with acceptable voltage deviation for nominal power of a power semiconductor converter.