Two types of low molar mass, medium vinylic polybutadienes containing 2-hydroxypropyl and 2-hydroxyethyl end groups were hydrogenated in the presence of several homogeneous Ziegler Ni catalysts prepared by using Ni(acac), and Ni(2-ethylhexanoate), as metal precursors and BuLi, Li adduct to a diene and Et3Al as activators. The catalytic efficiency of these systems determined by rate measurements showed that the best results can be achieved with the Ni(2-hexanoate)(2) + Li-diene (Ni : Li mol ratio = 1: 8-10) catalyst in the solvents commonly used in the synthesis of these polyalkadienes by anionic polymerization of 1,3-butadiene. As found by the kinetic study, the hydrogenation carried out under mild reaction conditions (temperatures of 10-35degreesC, hydrogen pressure of 72-178 kPa, Ni concentration of 2.1-10.0 mmol/dm(-3)) was the first order in the OH-polybutadiene and hydrogen and, over narrow range of catalyst concentrations (4.3-10.0 mmol Ni/dm(-3)), also in the catalyst. The activation energy of the hydrogenation estimated from the Arrhenius plot was 42 kJ/mol. Changes in the relative proportion of 1,2-, cis-1,4-, and trans-1,4-C=C units of the polymer during hydrogenation indicate the selectivity of the catalyst to the 1,2-hydrogenation. The ease of the addition of hydrogen to the internal C=C unsaturation was found to be opposite to that usually observed (trans > cis). The present low-pressure hydrogenation of both types of telechelic OH-polybutadienes proceeds with full retention of the average OH functionality and affords the saturated polymers, the residual C=C unsaturation of which (< 1%) has so far been usually achieved by high-pressure hydrogenations.