The influence of addition of Ir-oxide into Ni-Mo-oxide cathodes on the electrocatalytic activity of the hydrogen evolution reaction in acidic media was investigated. It was found that as the Ir-oxide content increased, the electrocatalytic activity towards hydrogen evolution also increased. This was attributed to the following two effects: the increase in the number of Ir surface sites and to the possible modification of the electronic structure of the material. Long-term electrolysis experiments confirmed high deactivation resistance of the Ni-Mo-Ir-oxide cathodes. It was also demonstrated that it is possible to in-situ reactivate the electrodes, making them potentially good cathode candidates for water electrolysis in the acidic medium. (C) 2019 Elsevier Ltd. All rights reserved.