The present invention relates to a method for electrolytic passivation of an outermost chromium or outermost chromium alloy layer for increasing the corrosion resistance of the outermost chromium or outermost chromium alloy layer, comprising the steps of: (i) providing a substrate comprising the outermost chromium or outermost chromium alloy layer, (ii) providing or preparing an aqueous, acidic passivation solution comprising: -Trivalent chromium ions, -Phosphate ions, -One or more organic acid residual anions, (iii) contacting the substrate with the passivation solution and passing a current between the substrate as anode and cathode in the passivation solution so that the passivation layer is deposited on the outermost layer, Here, in the passivation solution, the trivalent chromium ion is obtained by chemically reducing hexavalent chromium in the presence of phosphoric acid through at least one reducing agent selected from the group consisting of hydrogen peroxide and an organic reducing agent, However, during or after chemical reduction, one or more organic acid residual anions are first present in the passivation solution.
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