Chem. Commun., 2025, Accepted Manuscript DOI: 10.1039/D5CC04894J, Communication Hongbing Wang, Qiongdan Zhang, Xiaolin Zhou, Linsen Zhou, Wei Cui, Xiaoke Li, Peilong Li, Yifei Yang Support acidity is established as the decisive descriptor governing hydrogen spillover on non-reducible oxides. We reveal a unique reactant-induced activation pathway on γ-Al2O3, where optimal surface acidity empowers surface hydroxyls...