Such an activity improvement can be understood by the formation of oxidized domains on the Ni surface, which boosts HER activity in alkaline media by speeding up water dissociation at the oxide|metal interface . Recently it was shown that such potentiodynamic oxidation of Ni does not lead to surface roughening while increasing the HER exchange current densities 3-5 times . Still, the HER activity of oxidized Ni electrodes is very far from that of Pt (Figure , top row -pure Ni-poly). We also note that here we have observed rather high ORR activity of the Ni-poly electrode (consistently over five repeated measurement sets), with ηOER significantly lower compared to the previously reported value by McCrory et al., amounting to 0.46 V, which might be due to the lower roughness factor of Ni electrode in that particular work (RF = 2) . Also, we note that previously high OER activity of pure Rh electrode was reported, with the onset around 1.6 V vs. RHE (overpotential above 0.35 V), and it was also shown to be much more active than Pt (OER onset potential around 1.7 V vs. RHE) . For the Rh-modified electrodes, the situation is quite complex. First, the activities of the modified electrodes are close to or higher than that of platinized Pt, used here as benchmarks (Figure ), or previously reported in the literature (Table ). HER activity is higher for longer surface modification time (30 s). However, the effects of surface oxidation are different for two Rh exchange times. For 10 seconds exchange, the activity drops, but only slightly, and all the overpotentials are within 10 mV (Table ). In contrast, in the case of 30 seconds of exchange, the HER activity decays more but still remains higher than the activity Pt-poly (Figure , row -Rh@Ni-poly 30 s). Previously we have discussed similar effects induced by potentiostatic oxidation of Rh-modified Ni-poly electrode , suggesting that the oxidized phase of Rh-Ni could be less effective for H2O dissociation compared to the as-prepared Rh-Ni phase. Moreover, it was shown that the Rh-Ni phase offers better Hads energetics compared to the Ni surface.