Erbium- and oxygen-doped silicon was additionally doped with hydrogen, using plasma-enhanced chemical vapor deposition. Samples treated with solid-phase epitaxy (SPE) before hydrogenation and annealing at 900 ° C afterwards show a large enhancement of the photoluminescence (PL) yield. A change in local concentration leads to a dominance of the cubic center in the PL. Controlled etching shows that the PL stems from a deeper region with lower erbium concentration. The luminescence yield in the hydrogenated samples is significantly higher, even compared to samples optimized for cubic center luminescence. We thus conclude that hydrogen enhances the solubility of the cubic center in Si:Er,O.