Ln-dosed Ag/SiO2 (Ln = Eu and Yb) bimetallic catalysts were prepared by the reaction of SiO2-supported Ag (Ag/SiO2) with a solution of lanthanide metals dissolved in liquid ammonia. The catalytic properties were extensively studied by the hydrogenation of ethene and buta-1,3-diene. The hydrogenation behaviors varied markedly with the loading amounts of silver in the catalyst precursors (7, 20, 30 and 50 wt.% Ag/SiO2) and the lanthanide content in the bimetallic Ln-Ag catalysts. The activity increased with the loading of silver in the precursor and the lanthanide content, The catalytic nature of the bimetallic Ln-Ag surface drastically changed between the low and high lanthanide content, Ln-Ag/SiO2 exhibited changes in reactivity for ethene and buta-1,3-diene; thus in the region of low lanthanide content in Ln-Ag the order of decreasing activity for the hydrogenation was obtained as buta-1,3-diene and ethene, and reversely for higher contents, For the hydrogenation of buta-1,3-diene, but-1-ene and cis-but-2-ene were primarily produced in the region of low lanthanide content (0 < Yb/Ag < 0.15), while trans-but-2-ene was major for higher contents (0.15 < Yb/Ag).