This is a continuous process for producing hydrogen-rich gas. Successive beds of water-gas shift conversion catalysts of differing properties are employed in a shift converter to achieve an economical balance between catalyst activity and catalyst life. For example, a comparatively small fixed bed of highly active low temperature water-gas shift conversion catalyst may be loaded on top of a fixed bed of rugged low cost moderately active high temperature water-gas shift catalyst. A CO-rich gas and H.sub.2 O are introduced into the bed of low temperature shift catalyst where reaction takes place. The partially reacted gas stream leaves the bed of low temperature shift catalyst and is introduced into the bed of high temperature catalyst at a suitable temperature for triggering off therein the water gas shift reaction without the additon of heat from an external source. By this means it may be possible to produce hydrogen-rich gas with high conversions of CO to CO.sub.2, and to increase catalyst life at a moderate cost. It may also be possible to eliminate a feed heater or feed-product heat exchanger.