The peculiarities of electrochemical transformations (hydrogen and oxygen reaction) on a carbon-paste electrode containing А12Оз nanopowder were studied by cyclic voltammetry method. It was shown that 5-modification of Al203 has the highest reactivity in the hydrogen electrode reaction. Different behavior of Аl2О3 nanopowders under electrochemical study of the anode (oxygen) reaction and isotopic oxygen exchange with the gas phase have been explained by the effect of amorphous phase.