The finite analytical numerical method (FAM) combined with a conformal map has been used to study diffusion problems at a micro-ring electrode. The chronoamperometric and voltammetric responses for both reversible and quasi-reversible charge transfer at ring microelectrodes of different thicknesses are simulated, The effect of the thickness of the micro-ring electrode, the potential sweep rate and the heterogeneous electron transfer kinetic parameter on the voltammetric responses is discussed. The results show that the thin micro-ring electrode is more appropriate for the evaluation of fast electrode reaction rate constants than a thick micro-ring or microdisk electrode.