Numerical simulation is used to characterise double potential step chronoamperometry at a microband electrode for a simple redox process, A + e(-) reversible arrow B, under conditions of full support such that diffusion is the only active form of mass transport. The method is shown to be highly sensitive for the measurement of the diffusion coefficients of both A and B, and is applied to the one electron oxidation of decamethyl-ferrocene (DMFc), DMFc - e(-) reversible arrow DMFc(+), in the room temperature ionic liquid 1-propyl-3-methylimidazolium bistrifluoromethylsulfonylimide. Theory and experiment are seen to be in excellent agreement and the following values of the diffusion coefficients were measured at 298 K: D-DMFc = 2.50 x 10(-7) cm(2) s(-1) and DDMFc+ = 9.50 x 10(-8) cm(2) s(-1). (C) 2013 Elsevier B.V. All rights reserved.