The adsorption of atomic hydrogen has been studied on clean and potassium modified Cu(110) and Cu(100) surfaces. Two hydrogen induced states in the valence band have been found on the clean Cu(110) surface, an a state receding in the subsurface and a beta state in the surface of the crystal. Upon annealing, hydrogen in the subsurface both diffuses to the surface and desorbs at 330 K, and diffuses into the bulk. Two states, alpha (K) and beta (K), have also been observed on the potassium modified surfaces, with the aK state assigned to a potassium-hydrogen bond and the alpha (K) state assigned to a Cu-hydrogen bond. The Cu(110) surface is significantly more reactive than the Cu(100) surface.