An EmimAc/MWCNTs composite was prepared and characterized through SEM and TEM. The MWCNTs were well dispersed after combining with alkaline EmimAc. The activity of the composite was demonstrated by CV and controlled potential electrolysis. The composite could be used independently as electrolyte or electrode and showed excellent activity toward the electro-oxidation of the C-H bond of benzylic systems, and did so at a lower oxidation potential than when using EmimAc or MWCNTs. After modification, the pH value of the composite was adjusted to the acid range, and the yield of aldehyde adducts obtained through electro-oxidation improved. (C) 2016 Elsevier Ltd. All rights reserved.