NiCo-hydroxide on carbon cloth (Co0.5Ni0.5(OH)(2)/CC) is synthesized through chemical treatment of NiCo-phosphite/CC in alkali solution. Influence of oxygen content on the formation of NiCo-hydroxide/CC and electrochemical properties is studied. The fundamental formation process is speculated as ion-exchange and recrystallization. Experiment results reveal that dissolved oxygen in alkali solution accelerates the formation of hydroxides. Mass loading of active materials on CC can be up to 4.01 mg cm(-2), and the resulting flexible Co0.5Ni0.5(OH)(2)/CC demonstrates an excellent battery-like behavior with areal capacity 569.1 mu Ah cm(-2) at 10 mA cm(-2) and 479.2 mu Ah cm(-2) at 40 mA cm(-2) in hybrid supercapacitor. Moreover, the hybrid electrode exhibits excellent cycling stability with 80.0% capacity maintained after 8000 cycles, implying great promise in energy storage field. The above findings provide theoretical basis for preparation of NiCo-hydroxide through chemical treatment. (c) 2017 The Electrochemical Society. All rights reserved.