Epichlorohydrin (ECH) is a volatile organic compound and toxic to human health. Here we investigated clean mediated electrocatalytic dechlorination of ECH in aqueous solutions using electrogenerated [Nickel(I)(hexamethylcyclam)](+) ([Ni(I)(hmc)](+)) at glassy carbon cathode. Ni(II)/Ni(I) redox behavior of [Ni(II)(hmc)](2+), examined first by cyclic voltammetry in ECH free-aqueous solutions of various anions (Cl-, Br-, ClO4-, SO42-, phosphate, NO3-), showed only Cl- could provide most stable and reactive low-valent nickel species with highest versatility toward activation of ECH dechlorination. Cyclic voltammetry experiments over a range of scan rates and ECH concentrations elucidated rate limiting mechanism for Ni(I) catalyzed ECH dechlorination, and estimated catalytic reaction rate constant (k(cat)). ECH concentration-dependent k(cat) and i(cat) results revealed ECH dechlorination by Ni(I) followed Michaelis-Menten type inner-sphere electron transfer kinetics at low ECH concentrations (< 20 mM), but outer-sphere mechanism at higher concentrations. Interestingly, GC/MS showed complete destruction of ECH and production of three non-chloro products within 3-h bulk electrolysis. A possible mechanism was proposed for the overall Ni(I)(hmc)-catalyzed ECH dechlorination. Fast mediation kinetics, total removal of ECH, non-chloro organics as the only dechlorination products, and highly stable [Ni(I)(hmc)](+) mediator indicate electrocatalytic mediation using [Ni(I)(hmc)](+) in aqueous NaCl solution may be feasible for dechlorination of other organic chloro compounds. (C) 2017 Elsevier Ltd. All rights reserved.