The decomposition of methylene blue (MB) in aqueous solution was investigated using a dielectric barrier discharge in coaxial configuration operated in pulsed regime. The MB solution (volume=300 ml, concentration=50 mg/l) contained in a reservoir was circulated by a pump and made to flow as a film over the surface of the inner electrode of the plasma reactor. The best results were obtained when the discharge was operated in oxygen. The conversion of MB reached 95% after 30 min of plasma treatment and the corresponding yield was 57 g/kW h. Increasing the amplitude of the voltage pulses, and implicitly, the power dissipated in the discharge led to faster decomposition of the dye; however, the yield for MB degradation was lower. Better results were obtained for negative polarity of the applied voltage as compared to positive polarity, but after 30 min treatment the conversion had similar values for both cases. The gas flow rate did not influence the decomposition of MB in the range investigated, 300–900 ml/min. The solution flow rate had an effect on the dye degradation only for short treatment times, where a lower flow rate led to improved results, while for long treatment times the conversion was similar for 30 and 90 ml/min.