Effluents from reactive dyeing can be decolourised by cathodic reduction. The low dyestuff concentration requires use of electrolysers with high area. 80% decolourisation could be achieved at current efficiency of up to 8%. Energy consumption can be estimated with 5–6 kWh per 1 m3 wastewater. Careful selection of dyes is necessary to achieve irreversible decolourisation.