Inorganic oxide substrates are functionalized with silicon-free organic functionalizing agents. The organic functionalizing agent has a bonding functional group for bonding to the substrate and a functionalizing moiety that is not bonded to the substrate for imparting a desired functionality to the substrate. The functionalized inorganic oxide substrates are manufactured by selecting a functionalizing agent and reaction conditions that allows the bonding functional group to bond to the inorganic material while leaving the functionalizing moiety available for providing the desired functionality. The functionalized inorganic oxides can be used as filler materials in polymers or to manufacture a supported nanoparticle catalyst.