Fuel cell systems with in-block reforming

A fuel cell system comprises a fuel cell stack 102 with fuel and oxidant flowpaths, a cathode ejector 114 which receives oxidant from an oxidant supply 108 and recycled oxidant 124 from the fuel cell stack, and outputs combined oxidant 122 to the fuel cell stack, and an anode ejector 112 which receives fuel from a fuel supply 110 and recycled fuel 118 from the fuel cell stack, and outputs combined fuel 120 to the fuel cell stack. A recycle ratio of recycled fuel to fuel from the fuel supply being passed into the anode ejector is in the range of 4.5:1 to 15:1, preferably between 6:1 and 8:1. The fuel cell stack may be separated into two separate segments (103, 104; fig 2), with two anode ejectors (112, 113; fig 2) being provided for each fuel feed. In further aspects, a fuel cell system includes the anode ejector arrangement, in which (i) no unreformed fuel contained in the combined fuel mixture is reformed prior to being fed to said fuel cell stack, and (ii) the temperature of the fuel entering the fuel cell stack is no greater than the temperature of the combined fuel mixture output from the ejector.