NOVELTY - A reformer, for use in a fuel cell system comprises an enclosure including an inlet port and an outlet port; and a plate assembly supporting reforming catalyst disposed within the enclosure, where the outlet port is configured to abut a fuel inlet port of a fuel cell assembly adjacent to the reformer, when the reformer is assembled into the fuel cell system, so that at least a first portion of fuel reformed by the reformer is supplied directly from the outlet port of the reformer to the inlet port of the fuel cell assembly.    USE - The reformer is used in a fuel cell system (claimed).    ADVANTAGE - The present invention provides improved fuel cell stack design and methodology so as to create a fuel flow arrangement which increases the fuel conversion efficiency of the stack. It provides a fuel cell stack design and methodology which promotes cooling so as to realize a more uniform temperature distribution, thus increasing the overall efficiency of the fuel cell operation and electricity production and extending the operating life of the stack.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a fuel cell system comprising fuel cell assemblies and at least one reformer, forming a fuel cell stack, the fuel cell assemblies including at least one reformer-associated assembly and one or more non-reformer-associated assemblies, each the reformer-associated assembly being adjacent to and associated with a reformer, where each the reformer is configured to receive fuel through an inlet port and to output at least a first portion of fuel reformed in the reformer through an outlet port directly to a reformer-associated assembly associated with the reformer, and where each the reformer-associated assembly is configured to output partially spent fuel for use in one or more non-reformer-associated assemblies; and    (2) a method of operating a fuel cell system comprising at least one reformer and fuel cell assemblies including at least one reformer-associated assembly and one or more non-reformer-associated assemblies, by providing fuel to the at least one reformer; reforming the fuel using the at least one reformer; outputting at least a first portion of the fuel reformed by each the reformer directly to the reformer-associated assembly associated with the reformer; and outputting partially spent fuel from each the reformer-associated assembly for use in one or more non-reformer-associated assemblies.