A method for monitoring the total amount of sulphur containing compounds in a metal or metal alloy plating bath, wherein the sulphur containing compounds contain at least one sulphur atom having an oxidation state below +6, characterized in that the method comprising the steps: (a) providing a measuring sample comprising - one or more than one of said sulphur containing compound and - one or more than one reducing agent, wherein the one or more than one reducing agent is selected from the group consisting of compounds comprising at least one aldehyde group, preferably the one reducing agent is formaldehyde or the more than one reducing agent comprises at least formaldehyde, wherein a total amount of reducing agent in the measuring sample is selected such that the measured anodic oxidation current obtained in step (b) is at least 3 mA/cm 2 , (b) in a measuring unit comprising a working electrode, the electrode being contacted with the measuring sample applying a constant potential to the electrode such that the reducing agent is anodically oxidized at the electrode in the presence of the one or more than one said sulphur containing compounds, thereby generating an anodic oxidation current, and simultaneously measuring the anodic oxidation current to obtain current data, (c) optionally processing the current data of the measured anodic oxidation current obtained in step (b) to obtain processed current data, (d) comparing the current data obtained in step (b) or the processed current data obtained in step (c) with data or processed data, respectively, of at least one reference anodic oxidation current obtained from a reference sample comprising a reference total amount of said sulphur containing compounds. (a) providing a measuring sample comprising - one or more than one of said sulphur containing compound and - one or more than one reducing agent, wherein the one or more than one reducing agent is selected from the group consisting of compounds comprising at least one aldehyde group, preferably the one reducing agent is formaldehyde or the more than one reducing agent comprises at least formaldehyde, wherein a total amount of reducing agent in the measuring sample is selected such that the measured anodic oxidation current obtained in step (b) is at least 3 mA/cm 2 , - one or more than one of said sulphur containing compound and - one or more than one reducing agent, wherein the one or more than one reducing agent is selected from the group consisting of compounds comprising at least one aldehyde group, preferably the one reducing agent is formaldehyde or the more than one reducing agent comprises at least formaldehyde, (b) in a measuring unit comprising a working electrode, the electrode being contacted with the measuring sample applying a constant potential to the electrode such that the reducing agent is anodically oxidized at the electrode in the presence of the one or more than one said sulphur containing compounds, thereby generating an anodic oxidation current, and simultaneously measuring the anodic oxidation current to obtain current data, applying a constant potential to the electrode such that the reducing agent is anodically oxidized at the electrode in the presence of the one or more than one said sulphur containing compounds, thereby generating an anodic oxidation current, and simultaneously measuring the anodic oxidation current to obtain current data, (c) optionally processing the current data of the measured anodic oxidation current obtained in step (b) to obtain processed current data, (d) comparing the current data obtained in step (b) or the processed current data obtained in step (c) with data or processed data, respectively, of at least one reference anodic oxidation current obtained from a reference sample comprising a reference total amount of said sulphur containing compounds. <EOS>