To increase the pseudo-capacitance and cycle stability of polyaniline (PANI), PANI was covalently attached to reduced graphene oxide (rGO) via azobenzene (Azo) units. The rGO-Azo composite was first synthesized and subsequently used for the in situ chemical polymerization of aniline to form PANI-rGOAzo composites. The Azo units on rGO functioned as spacers to prevent the agglomeration of rGO and increase the solubility of rGO to assist in the in situ polymerization of aniline to form PANI-rGO-Azo composite. The Azo units act as linkers for the covalent attachment of PANI chains to graphene, thereby enhance the overall performance of the composite materials. The electrochemical properties of the composites were evaluated by fabricating symmetric two-electrode cell configuration and also compared with three electrode system. The charge transfer resistance of PANI is reduced from 6.6 ohm to 2.9 ohm, by grafting PANI onto rGO-Azo. The specific capacitance of PANI-rGO-Azo (328 F g(-1)) is higher than that of PANI (270 F g(-1)) and rGO-Azo (114 F g(-1)). The electrochemical performance of PANI was enhanced by grafting of PANI onto rGO-Azo. (C)2016 Elsevier Ltd. All rights reserved.