An efficient automated simulation of the transport-limited electrolysis in a channel flow cell, based on the multigrid method, is developed and is used to compute the working curve for the transport-limited current within the Leveque approximation. An accurate universal two-dimensional working surface (making neither the Leveque approximation nor ignoring axial diffusion) is presented for the steady-state transport-limited current from which the simulated response may be interpolated. The multigrid simulation is extended to include homogenous ECE kinetics and a working surface is presented for analysis of this mechanism within the Leveque approximation. This is then modified using a Gauss-Newton method to solve the nonlinear EC2E system for which an analogous working surface is generated. The effect of axial diffusion on the measurement of rate constants for these mechanisms is discussed. The merits of bilinear, cubic convolution, bicubic spline,and artificial neural network methods are assessed as interpolation methods for working surfaces. Working surface interpolation is shown to be a viable cost-effective alternative to repeated simulation methods, especially for problems of more than one dimension. A free data-processing service using the working surface data together with a suitable interpolation method is available via the World Wide Web (http:// physchem.ox.ac.uk:8000/wwwda).