A three‐dimensional finite difference computer simulation has been used to model an entire spherical volume conductor. The model permits conductivity to be dependent on distance from the center of the sphere. The method of successive overrelaxation is employed to solve the finite difference equations in a spherical nonhomogeneous, nonequidistant net. A new method of using successive overrelaxation along each space direction is presented. This method is very suitable for giving starting potentials of the normal successive overrelaxation.