A non-epitaxial growth method for the synthesis of Ag nanocubes by using Pt seed crystals was successfully developed. Tuning the amount of Pt seeds introduced into the reaction allowed for precise control over the size of the Ag nanocubes from 12 nm to 38 nm. Further experiments demonstrated the size-dependent properties of surface oxides and specific activities in terms of electrochemical surface areas for these Ag nanocubes to act as oxygen reduction catalysts in the KOH solution without and with methanol. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.