A series of alumino-silicates with an alumina content varying from 15 to 75wt.% were prepared by the sol-gel method. These oxides, modified or not with boria, were characterized by several techniques and used as supports for rhenium oxide. The resulting catalysts, after promotion with SnBu 4 , were evaluated in the metathesis of methyl oleate. The best system was obtained when 75wt.% Al 2 O 3 silica-alumina modified with 7.5wt.% B 2 O 3 was the support for 2wt.% Re 2 O 7 . FT-IR studies suggest that the catalytic activity is related to the Bronsted acidity of the support.