A composition is provided that can be used, for example, in a fuel processor for a fuel cell system. The composition includes a first material such as a catalyst, and a second material such as a desiccant. The second material is capable of sorbing and desorbing a heat transfer material such as water, and is present in an amount sufficient to sorb an amount of the heat transfer material sufficient to remove a portion of the heat generated when the first material undergoes an exothermic reaction.