In this paper we present a fully discrete A-ø finite element method to solve Maxwell’sequations with a nonlinear degenerate boundary condition, which represents ageneralization of the classical Silver-Müller condition for anon-perfect conductor. The relationship between the normal components of theelectric field E and the magnetic field H obeys a power-law nonlinearity of the type H x n = n x (|E x n|α-1E x n) with α ∈ (0,1]. We prove the existence anduniqueness of the solutions of the proposed A-ø scheme and derive the error estimates. Finally, wepresent some numerical experiments to verify the theoretical result.