Hydrogen is a component of spacecraft fuel that is explosive at atmospheric concentrations of four percent or higher. A study was undertaken to determine potential systems for use in tow types of hydrogen sensors that will be useful for real time hydrogen detection, both in ground storage and utilization facilities and in spacecraft. Quantitative detection demands a small, highly sensitive, and highly selective sensor. These detectors will be useful in areas such as the vicinity of joints, couplings, and stress points in the hydrogen storage and plumbing system of the space shuttle. Qualitative detection requires the other sensor to cover large areas, use no power, and be easily monitored visually or with a camera. Such a sensor will serve two purposes: it will allow general detection of hydrogen in a large space where poorly positioned point sensors would fail; it will also aid in locating and repairing any hydrogen leaks that might occur. A manganese (IV) oxide film was produced on the surface of a quartz crystal microbalance and this system was investigated for use as a small, quantitative hydrogen sensor. A reproducible response to hydrogen in the form of an increase in the frequency of vibration of the quartz crystal under an applied voltage was demonstrated. Other coatings were also investigated. A number of indicator compounds were screened for response to hydrogen to serve as large area sesnors. The metallochromic indicator, calmagite, produced a noticeable darkening upon exposure to hydrogen, demonstrating its potential for use as a qualitative, large area hydrogen sensor.