NOVELTY - An integrated reformer and combustion apparatus comprises at least one reformer plate (2) at which in use a reforming reaction can take place and at least one combustion plate (1) at which in use a combustion reaction can take place arranged in a stack so that the reformer plates and combustion plates are interspersed. It is arranged so that in use a reforming reaction and a combustion reaction can take place simultaneously, the combustion reaction providing heat for the reforming reaction.    USE - The integrated reformer and combustion apparatus is used in a fuel cell system to prepare hydrogen from a fuel and water.    ADVANTAGE - The heat produced by the combustion reaction taking place at the combustion plates is spread throughout the area in which the reforming reaction is taking place, to provide efficient heat transfer to the reforming reaction. The apparatus permits close control of the temperature of the combustion or reforming reactions. The efficiency of the combustion and reforming reactions can be maximized, and catalyst degradation and the generation of harmful gases can be avoided. By circulating fluid through the circuit the heat transfer between the combustion reaction and the reforming reaction is also improved. The additional circuit provides a way of achieving even closer control of the temperature of the system, however, as fluid having a pre-selected temperature can be circulated through the circuit to prevent fluctuations in temperature that may occur in the combustion or reforming reactions due to changes in the flow rates of gases through the apparatus.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a fuel cell system comprising the integrated reformer and combustion apparatus, and a fuel cell; and    (2) a method of preparing hydrogen from fuel and water using the apparatus.    DESCRIPTION OF DRAWING(S) - The figure is a perspective view of an integrated reformer and combustion apparatus.    Combustion plate (1)    Reformer plate (2)    Exhaust manifold (13)    Manifolds (15, 17)