The effect of hydrogen on electrochemical behavior amorphous metallic alloy based on cobalt has been studied. The alloy was charged with hydrogen in 0.5 M H2SO4 with addition 0.125 g As2O3. The X-ray analysis was used as the structural control method. It was established that hydrogenation brings about structural transformations of the surface layers of the amorphous ribbon analogous to those which happen in the case of annealing the specimen at the crystallization temperature.