Reaction of tris(pentafluorophenyl)boron with the silanol groups of MCM-41 resulted in the heterogeneous tris(pentafluorophenyl)borate anion. This immobilised weakly-coordinating anion retains metallocenes, thus yielding a heterogeneous propene oligomerisation catalyst. Activity comparable to the corresponding homogeneous catalyst can be obtained. The products typically consist of over 90% 1-alkenes with Flory–Schulz carbon number distribution.