A series of Ru-X-H-BEA (X = H+, Na+, Cs+) catalysts sulfided at high temperature in H2S (15%)/N-2 was characterized and tested in thiophene hydrodesulfurization (HDS) to analyze the effect of zeolite acidity and nature of the alkaline cation on the acid properties, stability of the sulfided phase and HDS catalytic activity. It is shown that after exchange of half of the zeolite protons by alkaline cations (Cs+, Na+) the acid properties of the zeolite are influenced by the nature of the cation suggesting the presence of a remote effect of the alkaline cation over the remaining sites and/or the disappearance of the most acidic sites. The activity of the catalysts and the product distribution in the HDS of thiophene are also influenced by the nature of the exchanged cation. Temperature-programmed reduction of the sulfided catalysts before and after thiophene HDS showed that a sulfided phase with low S/Ru ratio is obtained inside the zeolite channels. (C) 2008 Elsevier B.V. All rights reserved.