Reduced graphite oxide material (RGOM) has been prepared from potassium humate via a straightforward carbonization process at 700 degrees C for an hour. Potassium humate consists of a skeleton of alkyl/aromatic units cross-linked by a wide variety of oxygen-containing functional groups, and is considered as functionalized graphene platelets. The as-prepared RGOM possesses a specific surface area of 463 m(2) g(-1) and typical layered structure with a carbon/oxygen atomic ratio of 6.3, similar to the reduced graphite oxide (RGO) reported in literatures. The RGOM based electrode delivers high volumetric capacitance of 144 F cm(-3) at a current density of 0.05 A g(-1), as well as novel cycle performance. Its volumetric capacitance increases gradually during repeated galvanostatic charge-discharge (GC) in 3 M KOH electrolyte, and reaches to be (similar to 150% of the initial cycle) after 2000 cycles at a high current density of 2.5 A g(-1). The novel cycle performance is mainly attributed to the intercalation of OH and K+ into the interlayer of RGOM during charge-discharge process, and the increase of the available surface area for charge storage. (C) 2016 Elsevier Ltd. All rights reserved.