Scanning electrochemical microscopy (SECM) experiments were undertaken to study the EC' mechanism, e. g. where a product of the electrode reaction reacts to regenerate the starting material. Digital simulations of the two dimensional SECM were carried out and the results tested with the known EC' system of Fe(CN)(6)(4-)/cysteine for validation. The results were then used in SECM experiments with Ru(phen)(2)dppz(2+), a known DNA intercalator, to study the instability of the oxidized form in the absence and presence of DNA. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.056203jes] All rights reserved.