The reactions of F-2 with isomers of butene were investigated with crossed-beam reactive scattering and ab initio computations. Only one product channel F + C4H8F was observed in the experiments; the HF + C4H7F channel was searched but not found. The reaction path of F-2 + C4H8 -> F + C4H8F was studied theoretically. Very low barriers of less than 1 kcal/mol were found for the F-2 reactions with cis-2-butene, trans-2-butene, and isobutene, which all contain two methyl substitution groups. This theoretical prediction, yet to be confirmed experimentally, suggests that double methyl substituted C=C double bonds can react with F-2 almost without a barrier. (C) 2011 Elsevier B. V. All rights reserved.