In this study, Pd-Mo alloys have been internally oxidized to form Pd/MoO3 composites, and it is shown for the first time that H-2 reacts with these composites to form H-bronzes, for example, HxMoO3, within the Pd matrix. The Pd matrix is the source of mobile H atoms, which react with the oxide precipitates to form H-bronzes. The kinetics of H-bronze formation are extremely fast. Solubilities of H-2 in the Pd/MoO3 composites have been measured, and because H-2 solution in the oxide is so much more exothermic than that in the Pd matrix, the former can be separated from the latter. The intercept of the solubility plot along the H content axis gives the stoichiometry of the H-bronze formed. Some irreproducibility was found in the PH2 versus r relationships, which is also found in H-bronzes prepared by other techniques such as H spillover. The relative function of the H content of the bronze. The DeltaH(H) values decrease sharply in exothermicity with increasing x in HxMoO3.