The temperature distribution behind shock fronts and detonations through mixtures of oxygen with hydrogen, methane, methanol, ethylene and carbon monoxide has been studied by the method of spectrum-line reversal; simultaneously, measurements were made of pressure and shock speed. The spectrum and time history of the light emitted by the detonating gases were also examined. The detonations were initiated by shock waves from bursting diaphragms, and five basic types of record were obtained and are discussed separately: (1) fully established detonations; (2) detonations indicating a step down in temperature during the flow; (3) a condition just prior to detonation showing two light peaks or fronts; (4) a similar condition exhibiting only one of the fronts. (5) non-ignition. Conditions (3) and (4) were associated with irregularities in the tube wall due to window mountings; boundary-layer turbulence and transverse shocks are believed to cause these double fronts. The reasons for an apparent hyper-velocity region are discussed. Measurements of shock speed have yielded ignition temperatures for the particular mixtures studied.