A series of alumino-silicates with an alumina content varying from 15 to 75 wt.% 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 SnBu4, were evaluated in the metathesis of methyl oleate. The best system was obtained when 75 wt.% Al2O3 silica-alumina modified with 7.5 wt.% B2O3 was the support for 2 wt.% Re2O7. FT-IR studies suggest that the catalytic activity is related to the Bronsted acidity of the support. (C) 2003 Elsevier B.V All rights reserved.