Simulations of an ultramicroelectrode at the bottom of a conical well are presented, computed both for the potential step and linear sweep cases. The simulations are performed with direct discretisation on an unequally spaced grid, using the BDF algorithm. As the inclination of the conical wall goes from zero (vertically walled) to pi/2, the cell's behaviour, that is the response to a potential jump or an applied linear potential sweep, undergoes a transition between the vertical-walled recessed case and the planar UMDE case, as expected. Steady state conditions are considered, and current distributions across the electrode presented. Even at rather small inclination angles, the current density shows a large increase at the disk edge. The simulations can now be compared with experimental data. (c) 2006 Elsevier Ltd. All rights reserved.