Submicrometre particles of multiferroic BiMn2O5 are prepared by a hydrothermal method. We demonstrate for the first time that BiMn2O5-multiwalled carbon nanotube (MWCNT) composite can be used as a new active material for positive electrodes of electrochemical supercapacitors (ES). The possibility of fabrication of BiMn2O5-MWCNT composites from colloidal suspensions using Celestine blue dye as a co-dispersant for BiMn2O5 and MWCNT is demonstrated. The composite BiMn2O5-MWCNT electrodes with high mass loading and high active material to current collector mass ratio show a capacitance of 6.0 F cm(-2) (540 F cm(-3)) at a scan rate of 2 mV s(-1) and capacitance retention of 75 and 58% at scan rates of 100 and 200 mV s(-1), respectively. The new findings pave the way to the fabrication of efficient asymmetric devices, containing BiMn2O5-MWCNT positive electrodes and activated carbon-carbon black (AC-CB) negative electrodes. The asymmetric device shows good capacitive behavior and good cyclic stability in a voltage window of 1.8 V. The analysis of power-energy characteristics indicates that maximum energy density of 13.0 W h L-1 (9.0 W h kg(-1)) and maximum power density of 3.6 kW L-1 (2.5 kW kg(-1)) can be achieved. (C) 2015 Elsevier B.V. All rights reserved.