The catalytic activity of supported Ni/Ln(2)O(3) (Ln = La, Ce, Gd, Ho, Yb) catalysts for the hydrogen/water isotopic exchange reaction has been studied. The metallic and total surface areas were measured by hydrogen and krypton adsorption, respectively. The Ni surface area evaluated by hydrogen chemisorption is higher than the total BET surface area for Ni/La2O3. The Ni surface area does not change significantly while the total surface area increases with the decreasing Ln(3+) ionic radius. The thermodesorption spectra for the adsorbed hydrogen with and without preadsorbed H2O are reported. The mobility of the adsorbed hydrogen decreases from La2O3 to Yb2O3 as support and in the same direction decreases the water uptake normalised to the total surface area. The catalytic activity normalised to the Ni surface area decreases exponentially with the decreasing Ln3+ ionic radii from La2O3 to Yb2O3 as support, in close relationship with the basicity and hydration degree of the support oxide.