9,10-Anthraquinone-2-sulfonic acid Na-salt (AQS2), 9,10-anthraquinone-1,5-disulfonic Na-salt (AQDS1,5) and 1,4-dihydroxy-9,10-anthraquinone (DHAQ1,4) were investigated as to their ability to act as mediators for indirect electrochemical reduction of dispersed organic dyestuffs. A characterisation of the reducing efficiency was obtained from CV-experiments when comparing the cathodic current maxima of the AQ solution containing the dyestuff with the cathodic peak current without reducible vat dye. Voltammograms in a flow cell show that the limiting current density is dependent mainly on the diffusion transport of the AQ, while the addition of reducible dispersed dyestuff is of minor influence. Spectroelectrochemical experiments performed with 9,10-anthraquinone-1,5-disulfonic Na-salt in presence of Vat Yellow 1 permit a photometric observation of the coupled redox reactions.