The purpose of this talk is to prove the existence of chaotic traveling wave solutions for coupled arrays of Chua's circuits . Using the method of singular perturbations, we show that the ODE system for the traveling waves can have a heteroclinic loop consisting of two traveling waves moving at the same speed. Moreover, at the equilibrium points of the heteroclinic loop, the dominant eigenvalues of the system are a pair of complex numbers with negative real parts. By a generalization of Shilnikov's theorem of symbolic dynamics, the system can have chaotic behavior near the traveling heteroclinic orbits.