Abstract: The invention relates to a catalyst system (9), an electrode (1) which comprises the catalyst system (9), and a fuel cell (10) or an electrolyzer having at least one such electrode (1). The catalyst system (9) comprises an electrically conductive carrier metal oxide and an electrically conductive, metal oxide catalyst material. A near-surface pH value, called pzzp value (pzzp=point of zero zeta potential), of the carrier metal oxide and the catalyst material differ. The catalyst material and the carrier metal oxide form an at least two-phase disperse oxide composite. The carrier metal oxide has a first crystal lattice structure comprising first oxygen lattice sites and first metal lattice sites, wherein the carrier metal oxide on the first oxygen lattice sites is preferably doped with at least one element from the group comprising nitrogen, carbon, and boron, and is optionally additionally doped with hydrogen.