A novel type of composite xerogel can be obtained by the combination of polyvanadic acid and bentonite clay. displaying a characteristic green colour, associated with the presence of vanadium(IV) sites and intervalence-transfer bands in the near-infrared region. The slow evaporation of the xerogel suspensions leads to lamellar solids containing vanadium(V) oxide and silicate layers. In contrast to the vanadium-oxide films, the composite xerogels are not soluble in water, showing a good electrochemical response when applied onto electrode surfaces. Enhanced electrochemical signals are observed in the presence of electroactive species such as the hexaammineruthenium(II) complexes, reflecting their intercalation into the interlamellar space.