HER and OER activity of Ni and Rh-modified electrodes was measured using a specific protocol, which was started immediately after the electrode transfer to the electrochemical cell. The program for the HER and OER activity measurements was constructed in such a way as to avoid undesirable anodic excursions of studied electrodes or any equilibration at the open circuit potential (OCP). For all the measurements IVIUM Vetex.One potentiostat was used. Measurements were done in a onecompartment, three-electrode electrochemical cell with a Saturated Calomel Electrode (SCE) as a reference electrode and a 3×3 cm Ni foam (Goodfellow Cambridge Limited, England) as a counter electrode. The electrolytic solutions were prepared using KOH (Sigma Aldrich) and ultrapure deionized water. All the measurements were done at room temperature. Here, the potentials are referred to as the Reversible Hydrogen Electrode (RHE) scale by directly measuring the potential of the used reference SCE electrode versus the RHE formed in the corresponding electrolytic solutions. Electrolyte resistance was corrected using hardware settings, but only to 70 % of the resistance value. The electrolyte resistance was determined using single-point impedance measurement at -1 V vs. SCE (approx. 0 V vs. RHE). The gasses used in this study were of 99.999 % purity.