Oxide materials with rhenium(V) oxochloro complexes highly dispersed on the surface were prepared by grafting Re(V) alkoxochloro complexes onto gamma-Al2O3, chlorinated alumina, 25 and 75 wt% SiO2 silica-aluminas, mesoporous alumina with high specific surface area (685 m(2)g(-1)) and mesoporous silica-alumina (950 m(2) g(-1)). The activities of these catalysts for 1-octene metathesis at room temperature are compared in the presence of a promoter: Bu4Sn or Ph2SiH2. Systems consisting of pure alumina and chlorinated alumina supports with rhenium species and Bu4Sn lead to :;elective formation of 7-tetradecene and ethylene at 90-100% conversion. There is a dramatic change of selectivities with Bu4Sn and silica-alumina or with Ph2SiH2 and aluminas. The difference is attributed to the formation of hydrido and carbene rhenium surface species which promote at the same time isomerization, self- and cross-metathesis. Mesostructured oxides do not: show any clear advantage over commercial supports. Interestingly, modifying gamma-alumina with hydrogen chloride increases the catalytic activity even at low rhenium loading (ca. 0.7 wt%). (C) 2008 Elsevier Inc. All rights reserved.