Single electrode materials capable of both electric double-layer and Faradic redox-based pseudo capacitance can be used for fabrication of high performance supercapacitors in an easy way and thus are highly desirable in the energy storage field. This contribution reports a new kind of such materials based on alkylated graphene materials (C(n)rGO, n is the carbon number of their alkyl side chains) having different alkyl side chains (n = 4, 8, and 16). These materials were prepared via esterification of KOH-treated GO with the corresponding alkyl bromides in the presence of a phase transfer catalyst. More importantly, water was used as the reaction medium, and thus endowing the preparation method an eco-friend feature. The so-prepared graphene materials displayed chain length-dependent specific surface area and the population of residue CAO functionalities, and thus affording vast differences in their supercapacitor behaviors. C(4)rGO, the product having butyl side chains, showed the best supercapacitor performance with a capacitance up to 242.2 F g(-1) at a scan rate of 100 mV s(-1) and a good cycling stability. (C) 2015 Elsevier Ltd. All rights reserved.