The effects of organosulphonate groups on the ion-exchange and ion-transport properties of silica hydrogels have been investigated by using Ru(NH 3 ) 6 3+ , Ru(bpy) 3 2+ and Fe(CN) 6 3− redox probes. Silica and sulphonated ormosil hydrogels were prepared by using tetramethyl orthosilicate as a silica precursor and 2(4-chlorosulphonylphenyl)ethyl-trichlorosilane to provide sulphonate functionality for ion-exchange and ion conductivity. Both gels act as cation-exchangers and exclude Fe(CN) 6 3− . Partition coefficients are higher for the ormosil and for the more highly charged Ru(NH 3 ) 6 3+ versus Ru(bpy) 3 2+ . Diffusion coefficients are higher for the unmodified silica, which is consistent with weaker interactions between the cationic probes and less anionic gel network.