The catalytic activity of hybrid organic–inorganic silica glasses doped with the ruthenium species tetra-n-propylammonium perruthenate (TPAP) in the aerial oxidation of alcohols to carbonyl compounds, either in toluene or in dense-phase CO2, substantially increases with time several months after the xerogels' preparation, yielding the most active ruthenium-based aerobic-oxidation catalysts reported thus far. The doped sol–gels are living materials, and an explanation of the observed reactivity enhancement is given, which is thought to have general validity for future applications to a wide variety of relevant heterogeneous processes.