Hydrogenations of several hydroxy-terminated low molecular weight polybutadienes (PB) or non functional PB and one polyisoprene by homogeneous catalysis were studied. Hydrogenation of 1,4-polybutadienes gave solid crystalline polymers. In the case of hydrogenated 1,2-polymers a decrease of the glass transition temperature was noted, the hydrogenation leading to amorphous polymers. The rheological behaviour of oligomers was found to be Newtonian at low shear rates (≤ 100 s−1). The viscosity at Tg+100°C increased in every case with the hydrogenation rate. It was found that hydrogen bonding induced by hydroxyl groups has a great effect on the glass transition temperature but does not change the viscosity at Tg + 100°C.