The analysis of current transients during electrochemical machining (ECM) at a planar workpiece planar tool configuration results in the determination of the important parameters for the ECM process. These have been used in finite difference simulation of the ECM process, which allows simulation of the current transients and tool and workpiece configurations at any time for non-planar configurations more applicable to industrial ECM. Small differences in the simulated and experimentally observed current transients are often observed, which can be attributed to variation of the combined ECM parameter k with current and electrolyte flow path length. Measurement of these variations has been achieved for In718 by current transient analysis of experimental data obtained from the ECM of a planar workpiece-planar segmented tool configuration. Variations in valency have also been measured for SS316 using this configuration. This information has then been used to improve the finite difference simulation. This approach has been shown to increase the accuracy of both materials characterisation and process simulation in ECM. (C) 2003 Published by Elsevier Science B.V.