Amorphous MnO2 was attached to carbon nanotubes (CNTs) in 60 seconds by solid-state microwave method. As electrodes in supercapacitors, the coactions of the MnO2 and CNT augmented the actual value of capacitance to 1250 F g(-1), and cycle steadiness held 80% of the starting value after 7000 cycles. The equipped MnO2/CNT//AC asymmetric supercapacitor (ASC) manifested preferable energy density with 33.5 Wh kg(-1) (at 400 W kg(-1)). Its glorious electrochemical properties of MnO2/CNT demonstrated that the microwave method has great potency to realise the composite of electrode materials.