The recyclability of the 2 wt.% Re2O7/7.5 wt.% B2O3/SiO2-Al2O3 catalytic system upon activation with SnBu4 was evaluated in the metathesis of methyl oleate. The activity and selectivity of this system were kept almost constant for 25 runs, but after 31 runs the catalyst was completely deactivated. XPS analyses showed that tin oxide covers selectively rhenium and boron sites. When all rhenium atoms are covered, the catalytic activity is extinguished. (C) 2004 Elsevier B.V. All rights reserved.27441671213217