In this study the selective extraction of cycloolefins from their mixtures with cyclohexane by chemical complexation with silver ions in ionic liquid solutions has been performed. The solubilities of cyclopentadiene (CP) and dicyclopentadiene (DCP) in the reactive medium, silver tetrafluoroborate dissolved in 1-butyl-3-methylimidazolium tetra fluoroborate, were investigated. Experimental results were obtained working at different concentrations of cycloolefins (100-1000 ppm) in the organic phase and at a temperature range between 283 K and 323 K. The solubility of the olefins is substantially determined by the concentration of the silver ions, an increase in the metal content of the solutions being associated with a strong increase in solubility. Experimental results show that this process allows purification of cyclohexane reducing also the content of cycloolefins down to few parts per million (ppm). Furthermore, the use of BMImBF4 as extraction media involves important advantages due the regeneration capacity. (C) 2009 Elsevier B.V. All rights reserved.