Electron acceleration by a wave propagating obliquely in a magnetized plasma is considered. For wave amplitudes above the stochasticity threshold the motion of electrons is diffusive. A test of a simple diffusion formalism is presented. We reduce the diffusion equation to a one-dimensional form by transforming to a coordinate system that has the Hamiltonian as one of the axes. We present a model for the diffusion coefficient and solve the resulting diffusion equation by means of the finite element technique. The results are compared with numerical solutions of the orbits. Finally, we apply our results to the problem of electron diffusion in the lower ionosphere. ¿ American Geophysical Union 1991