Abstract: Process for the alkaline passivation of galvanized and alloy-galvanized steel surfaces and of aluminum in strip lines, wherein the metal surfaces are brought into contact with an alkaline aqueous solution that contains complexing agents and iron, which has a free alkalinity in the range of 5 to 20 points and a total alkalinity in the range of 7 to 30 points and contains: 0.1 to 1 g/l magnesium ions, 0.1 to 1 g/l iron (III) ions and 0.5 to 5 g/l amino or hydroxy carboxylate ions. This may be followed by a chrome-containing or chrome-free secondary passivation.