NOVELTY - A precursor (P1) for production of an electrode for gas evolution in electrolytic processes, comprises: ruthenium nitrate dissolved in a chloride-free aqueous solution containing acetic acid (higher than 30 wt.%).    USE - For preparation of precursor for production of electrode for gas evolution (preferably electrode for cathodic hydrogen evolution) in electrolytic processes (claimed).    ADVANTAGE - The precursor for production of electrode for gas evolution in electrolytic processes, such as electrode for cathodic hydrogen evolution, provides improved electrode (i.e. cathode) composition for industrial electrolytic processes, having equivalent or higher catalytic activity of prior art formulations, lower overall cost in terms of raw materials, higher reproducibility of preparation and lifetime and tolerance to accidental current reversal equivalent or higher in the usual operative conditions. The catalytic later also contains 1-10 g/m2 of rare earths e.g. praseodymium, in form of oxides, and optionally 0.4-4 g/m2 of palladium. The precursor comprises nitrate of ruthenium dissolved in chloride-free solution containing (more than 30, preferably 35-50) wt.% of acetic acid. The activity, duration and tolerance to reversals of electrodes used as cathodes for hydrogen evolution, catalyzed with ruthenium provide remarkably superior result, when nitrate-based precursors in substantially chloride-free acetic solution are used in manufacturing the electrode, instead of common precursor of prior art consisting of RuCl3 in hydrochloric solution. This may be due to formation of complex species, where ruthenium atom is co-ordinated with acetic or carbonyl groups, in absence of co-ordination bonds with chloride; and this complex species imparts morphological, structural or compositional effects reflected in improved performances of electrode obtained by means of their decomposition especially in terms of duration and current reversal tolerance. The nitrate of ruthenium employed is Ru (III) nitrosyl nitrate, which is also easily available in amounts sufficient for industrial production of electrodes. The precursor solution also comprises rare earth nitrates, which have advantage of providing further stability to electrode coating obtainable by thermal decomposition of same precursor. The addition of Pr(NO3)2 imparts desirable features of functioning stability and tolerance to current reversals to coating obtained by decomposition of precursor. The precursor solution also comprises palladium nitrate; where presence of palladium in coating obtainable by thermal decomposition of precursor has advantage of imparting enhanced tolerance to current reversals, especially in long term.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) method (M1) for preparation of the precursor (P1) for production of electrode for gas evolution in electrolytic processes, involving: preparation of a ruthenium solution by dissolution of ruthenium in glacial acetic acid under stirring, with optional addition of nitric acid, followed by a dilution with an aqueous solution of acetic acid (5-20 wt.%);    (2) method (M2) for manufacturing electrode for gas evolution in electrolytic processes, involving: application of the precursor (P1) to a metal substrate in multiple coats, with thermal decomposition at 400-600 degrees C for not less than 2 minutes after each coat; and    (3) electrode for cathodic hydrogen evolution in electrolytic processes comprising: a metal substrate coated with a catalytic layer containing 4-40 g/m2 of ruthenium in the form of metal or oxide obtainable by the method (M2).