Methods and related systems for determining an efficient operating state for an integrated fuel cell/fuel reformer power system have been developed. Such a method forms the basis of a control strategy for an integrated system. The method describes optimization of the efficiency of operation of a power system comprising a fuel processor and a fuel cell operating in an integrated way. Maps of the operating properties of the system components are determined by experiment. For any desired power level, a unique vector of control setpoints can be calculated from these known properties of the subcomponents and the system, which vector of values can be used to set the values of system controls to a state that optimizes the system efficiency at the specified power output.