A combined catalyst and sorbent was developed for reacting CO with steam to produce H₂ in a single reaction stage at 600 °C by employing the water gas shift (WGS) reaction. The combined material was in the form of spherical pellets where each pellet consisted of a CaO core for absorbing byproduct CO₂ surrounded by a porous shell of Al₂O ₃ which supported a Ni catalyst. The best results were achieved by incorporating 5 wt % limestone in the shell material to suppress coking. By employing the best core-in-shell pellets and supplying a 3:1 mol ratio of steam to CO at 600 °C, more than 97% of the CO was converted to H₂ by the WGS reaction and less than 1% was converted to CH₄ by a side reaction. Also, none of the CO was converted to coke.