The composite electrode material for supercapacitors includes mesoporous manganese dioxide (MnO2), graphene oxide, and nanoparticles of molybdenum disulfide (MoS2). The composite material is prepared by preparing mesoporous manganese dioxide, preferably by surfactant-assisted precipitation, then mixing graphene oxide with the mesoporous MnO2 is ethanol and ultrasonicating, and finally nanoparticles of MoS2 are mixed with the suspension of graphene oxide and mesoporous MnO2 to form the composite electrode material. The capacitance of the material may be varied by changing the concentration of MoS2 nanoparticles. Samples of the composite electrode material exhibited good supercapacitance values, such as 527 and 1160 F/g.