Quinone molecules have been widely studied as effective redox-active species for supercapacitors, but an understanding of the adsorption of quinones on activated carbon electrodes is very scarce. A hydroquinone molecule does not form a strong bond on pristine graphene, Stone-Wales defect, and double-vacancy surfaces, but it forms strong adsorption on single-vacancy surface. We demonstrate from first-principles calculations for various quinones that selecting an appropriate surface model is crucial in conducting a proper comparative study of the adsorption of quinone molecules. We suggest the single-vacancy graphene surface as a useful model for studying the adsorption of quinone molecules on an activated carbon electrode. (C) 2016 Elsevier B.V. All rights reserved.