During cryogenic weigh system operation, hydrogen when combined with oxygen can create an unsafe condition. Therefore the concentration of the residual oxygen and hydrogen from leaks in the cryogenic weigh environmental bags must be known at all times during the cryogenic weigh. Hydrogen and oxygen detectors will provide the optimum method for maintaining safe conditions. Hydrogen properties and safe mixtures are reviewed. The method selected to analyze the oxygen content is discussed. The selection, development, and testing of a hydrogen detector system is examined.