The previous improvements of HER activity were achieved using similar approaches, like spontaneous deposition of Pd and Rh on smooth Pt-poly (RF 2) , where Rh-modified Pt-poly showed higher HER activity than Pd-modified Pt-poly, without significant change of the roughness factor (2.1 for Rh-modified surface, and 2.08 for Pd-modified surface). Described catalytic surfaces should also be compared to pure Rh, and recently Rh films on Ni foam and Ti mesh, prepared by aerosol-assisted chemical vapor deposition (AACVD) technique, were investigated as HER catalysts in alkaline media . It was found that Rh film on NF had η 10 of -127 mV, while the one prepared on Ni mesh had the corresponding overvoltage of -67 mV . As there are many studies of HER catalysts in alkaline media, it would be possible to extend the comparison with literature data to a large number of reports. However, here we refer to the review of Bouzek et al. and Rh 3+ and metallic Rh (from Ni 3d high-resolution spectra) . The results shown are for 10 s exchange with Rh, in which case neither electrochemistry nor SEM shows the formation of welldefined Rh islands, but it is obvious that there are certain parts of the surface containing Rh aggregates. However, after 30 s exchange with Rh, there are clear indications that Rh islands are formed, and the effect is more prominent for higher exchange times. For example, after 45 s of exchange with Rh, the characteristic H UPD region is clearly seen (Figure ), which is the feature of the Rh phase . This observation unambiguously confirms that longer exchange times lead to the formation of metallic Rh islands on the Ni-poly surface.