A gas-filled overvoltage arrester with an electrode activation compound. In order to ensure a high degree of adherence of the activation compound to the electrodes in a gas-filled hydrogen-containing overvoltage arrester, the activation compound comprises a first aluminum component, a second halide component, and a third dielectric or ferroelectric metal oxide component. These three components are present in the proportions of 50 to 70, 20 to 40, and 3 to 10 mol. %, respectively.