Two-dimensional transition metal carbides, MXenes, with large surface area, excellent electrical conductivity and chemical stability, have proved promising for energy storage. However, the irreversible re-stacking and low capacity of MXenes restrict their development and practical applications. Here, the N-doped carbon decorated MXene (Ti3C2Tx@NC) composites were synthesized via an in-situ selfpolymerization of dopamine on the surface of Ti3C2Tx followed by a carbonization process. The Ti3C2Tx and Ti3C2Tx@NC were systematically characterized, which have been manifested that NC were equably decorated on the surface and interlayer of Ti3C2Tx sheets and a unique three-dimensional composited nanostructure was fabricated. Such nanostructure can confer both high surface area of NC layer and effective avoidance of the restacking of Ti3C2Tx sheets, whilst, importantly, rendering the composites good conductivity and additional pseudocapacitance. As a result, the optimized Ti3C2Tx@ NC-2 composite exhibited a high specific capacitance of 442.2 Fg(-1) under a current density of 1 A g(-1), which is 281% higher than that of Ti3C2Tx. As a further description, Ti3C2Tx@NC achieved an excellent cycling stability with capacitance retaining 91.9% after 5000 cycles and a high rate capability of 92.5% at 10 A g(-1). Besides, the Ti3C2Tx@NC-(2)-based symmetric supercapacitor presents a delighted energy density and power density. Therefore, the elaborately designed Ti3C2Tx@NC composites provided a pregnant exploration for energy-related applications. (C) 2017 Elsevier Ltd. All rights reserved.