NOVELTY - Hydrocarbon fuel (60) is converted to hydrogen rich fuel reactant gas stream by reformer (76). Shift converter (84) and selective oxidizer (90) remove the majority of undesired carbon monoxide gases created by reformer when converting fuel to hydrogen. Boiler (56) provides steam to the reformer, allowing replacement of acid electrolyte fuel cell without compromising its advantages.    USE - Electricity generation.    ADVANTAGE - The power plant operates at lower fuel cell temperatures and coolant pressures such that overall size and manufacturing cost of the power plant are reduced.    DETAILED DESCRIPTION - The proton exchange membrane (PEM) fuel cell power plant comprises:    (a) cell stack assembly of PEM fuel cells, each cell comprising cathode, anode and PEM between cathode and anode;    (b) cell stack assembly cooler;    (c) device for providing oxidant reactant gas to cathode; and    (d) device for providing fuel reactant gas to anode, comprising:    (i) a steam producing boiler;    (ii) reformer for receiving the hydrocarbon fuel and the steam and producing a fuel reactant gas comprising hydrogen and carbon monoxide;    (iii) shift converter for receiving fuel reactant gas from the reformer and converting a portion of the carbon monoxide in the fuel reactant gas to carbon dioxide; and    (iv) a first selective oxidizer for receiving fuel reactant gas from the shift converter and oxidant reactant gas from the oxidant reactant gas providing device, and converting a further portion of the carbon monoxide in the fuel reactant gas to carbon dioxide.    A second selective oxidizer can be included for receiving fuel reactant gas from the selective oxidizer and oxidant gas from the oxidant reactant device, and converting a portion of the carbon monoxide in the reactant fuel gas to carbon dioxide.    An INDEPENDENT CLAIM is given for operating a PEM fuel cell power plant.    DESCRIPTION OF DRAWING(S) - The drawing shows a PEM fuel cell in a power plant.    Power plant (10)    Fuel cell (12)    Anode (14)    Cathode (16)    Cooler (18)    Proton exchange membrane (20)    Boiler (56)    Shift converter (84)    Selective oxidizer (90)