A steam methane reforming method in which a feed stream is treated in a reactor containing a catalyst that is capable of promoting both hydrogenation and partial oxidation reactions. The reactor is either operated in a catalytic hydrogenation mode to convert olefins into saturated hydrocarbons and/or to chemically reduce sulfur species to hydrogen sulfide or a catalytic oxidative mode utilizing oxygen and steam to prereform the feed and thus, increase the hydrogen content of a synthesis gas produced by a steam methane reformer. The method is applicable to the treatment of feed streams containing at least 15% by volume of hydrocarbons with two or more carbon atoms and/or 3% by volume of olefins, such as a refinery off-gas. In such case, the catalytic oxidative mode is conducted with a steam to carbon ratio of less than 0.5, an oxygen to carbon ratio of less than 0.25 and a reaction temperature of between about 500 C. and about 860 C. to limit the feed to the steam methane reformer to volumetric dry concentrations of less than about 0.5% for the olefins and less than about 10% for alkanes with two or more carbon atoms.