We apply transition state theory as developed by chemists to the classic problem of chaotic ionization of hydrogen in crossed fields. As one cannot define a potential energy surface for this problem due to the existence of the magnetic field, one must generalize the chemist's approach. In this process we find a "periodic orbits dividing surface" (PODS) in phase space as opposed to coordinate space. Using this PODS we investigate the dynamical processes that lead to the ionization of the hydrogen atom. The result is that we are able to make the connection between the classical rate of ionization and the fractal properties of the nonlinear dynamics.