Abstract: A safety monitoring system for an immersion cooling system of a large, high-density electronic assembly such as a supercomputer protects against the possibility of toxic gas formation due to overheating and breakdown of the cooling liquid caused by a system failure. Voltage taps are provided on all of the power supply bars in the computer, and are brought out to the monitoring system, which scans them and compares them against predetermined voltage tolerance limits. A catastrophic electronic failure or short circuit within the computer could produce arcing that could cause local high temperatures and coolant breakdown. The reduction in voltage caused by such failure would immediately be detected by the monitor, which would operate to shut down power to the computer, and activate a safety ventilation system prior to any substantial production of toxic gas.