A direct oxidation fuel cell (DOFC) system, comprises at least one fuel cell assembly including a cathode and an anode with an electrolyte positioned therebetween, adapted for performing selected electrochemical reactions; a source of concentrated liquid fuel in fluid communication with an inlet of the anode; an oxidant supply in fluid communication with an inlet of the cathode; a liquid/gas (L/G) separator in fluid communication with outputs of the anode and cathode for receiving unreacted fuel and liquid and gaseous products of the electrochemical reactions; and a converter for catalytically converting a portion of the unreacted fuel to the liquid and gaseous products.