an electrochemical gas sensor includes a housing and with at least one electrode . the housing has a gas inlet . an at least strongly acidic , liquid electrolyte is present in the gas sensor . the electrolyte partly wets the electrode . provisions are made in such a gas sensor for the electrolyte to contain an additive that contains at least one surfactant . an electrolyte is also provided for a gas sensor , which electrolyte contains at least one surfactant as an additive .