Abstract: A shock tube has been built for the purpose of studying ignition of fuel-air mixtures. Some theoretical considerations related to design are presented. This shock tube includes a driver, a buffer, and a test section. The gasoons fuel-air mixture is placed at the shock reflection end, and is compressed first by the incident shock, then by the reflected shock, all in a very short time. The gas can be compressed to pressures from 6 to 20 atmospheres and temperatures from 800 to 1100 deg. K.Instruments used to study the shock and the ignition include fast-response pressure pickups for instantaneous pressure and shock-velocity measurements, photo-multiplier for radiation measurement, and high-speed motion picture camera for detailed study of the inflammation process. The results show that, by taking real gas behavior into account, the state of the fuel-air mixture can be calculated accurately from measurements of shock velocity. This shock tube is adequate for testing hydrocarbon-air mixtures with ignition delays ranging from a fraction of a millisecond to a few milliseconds. High speed motion pictures show that the ignition of several fuel-air mixtures is similar to the observations made with rapid-compression machines. From ignition-delay data, the reaction which leads to the final rapid inflammation of the stoichiometric n-butane-air mixture is found to have an apparent reaction order of 1.8 and an apparent activation energy of 17,000 calories per gm mol.