Here we report an approach to design composite cathode based on TiOx nanotubes decorated with RuOx nanowhiskers for efficient hydrogen evolution. We tailor catalytic activity of the cathodes by adjustment of morphology of TiOx nanotubular support layer along with variation of RuOx loaded mass and assess its performance using electrochemical methods and wavelet analysis. The highest energy efficiency of hydrogen evolution is observed in 1 M H2SO4 electrolyte to be ca. 64% at -10 mA/cm(2) for cathodes of the most developed area, i.e. smaller diameter of tubes, with enhanced RuOx loading. The efficiency is favored by detachment of small hydrogen bubbles what is revealed by wavelet analysis and is expressed in pure noise at wavelet spectrum. At increased current density, -50 or -100 mA/cm(2), better efficiency of composite cathodes is supported by titania nanotubes of larger diameter due to an easier release of large hydrogen bubbles manifested in less periodic events appeared in the frequency region of 5-12 s at the spectra. We have shown that efficiency of the catalysts is determined by a pre-dominant type of hydrogen bubble release at different operation regimes depending on specific surface and a loaded mass of ruthenia. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.