Direct current (DC) voltammetry and differential pulse (DP) voltammetry using a carbon paste electrode (CPE) have been used for the determination of trace amounts of ecotoxic 1,2-diaminoanthraquinone (DAAQ). The limit of determination ( L D ) of DAAQ for DC voltammetry was 2 × 10 –6 mol l –1 , and for DP voltammetry 2 × 10 –7 mol l –1 under the optimized conditions in a mixed Britton–Robinson buffer pH 12 and methanol (1:9) medium. Adsorptive accummulation of the analyte on the surface of CPE decreased the limit of determination to 2 × 10 –8 mol l –1 for DP voltammetry. Practical applicability of these newly developed methods was verified on model samples of river water.