A polythiolated-beta-cyclodextrin polymer was synthesized and used as a coating material for gold electrodes. The functionalized electrodes were employed for immobilizing adamantane-modified horseradish peroxidase via supramolecular associations. The enzyme-containing electrode was used as an amperometric biosensor device with 1mM hydroquinone as electrochemical mediator. The biosensor exhibited a fast amperometric response (10s), a good linear response toward H(2)O(2) concentrations between 28 microM and 5.5 mM, and a low detection limit of 7 microM. The biosensor showed a sensitivity of 109 microA/Mcm(2) and retained 98% of its initial electrocatalytic activity after 40 days of storage at 4 degrees C in 50mM sodium phosphate buffer pH 7.0. The host-guest supramolecular nature of the immobilization method was confirmed by cyclic voltammetry.