The catalytic properties of lanthanides (Ln) deposited on oxides (MnO, TiO2 and MgO) from Eu or Yb metal solutions in liquid ammonia were studied. The catalysis of Ln/oxide varied markedly with differences in the oxides used and changes in levels of lanthanide content. The thermal treatment of Ln/oxide in vacuo also led to appreciable changes in catalytic activity. The lanthanides were used more efficiently for the hydrogenation and dehydrogenation when deposited on MnO. Ln/MnO showed the highest activity for the hydrogenation of ethene. Upon introduction of more than ca. 8 mass% Eu or Yb onto MnO, the activity for the hydrogenation appeared even at a reaction temperature of 199 K. The adsorption characteristics of hydrogen evaluated by temperature-programmed desorption (TPD) were improved at the same time. The lanthanide species present on MnO were characterized by FT-IR, combined with TPD studies. The increase in catalytic activity of Ln/MnO with evacuation temperature was responsible for changes of lanthanide amide to imide. In particular, when Ln/MnO was evacuated around 673 K, some synergetic actions between the lanthanides and MnO maximally develop, leading to enhanced activities.