Adiabatic prereforming is a well-established process in modem syngas production and implies both economic and operational benefits. The adiabatic prereformer converts hydrocarbon feedstocks by steam reforming reactions in the low temperature range, 350-550 degrees C. Design aspects of adiabatic prereforming are reviewed. Reaction kinetics, poisoning and transient deactivation and limits for carbon formation have been formulated as mathematical models and implemented into reactor simulation programs. Operation close to the carbon limits are illustrated by examples from experimental development work. Industrial operation and benefits are illustrated by examples from units operating in plants producing hydrogen, ammonia and carbon monoxide.