Oligomerization of isobutene has been carried out using silica supported Bronsted acidic ionic liquid catalysts. Silica supports with different particle size and textural properties have been used to prepare the catalysts. A close relationship between these properties and catalytic activity of the SILP material was observed. Silica supports with mesoporous structure could be converted to very active catalysts. On the other hand, the use of microporous supports resulted in the formation of catalysts with excellent C-12 selectivity. (C) 2013 Elsevier B.V. All rights reserved.