An unusual ‘dimerization’ of CF3-allyl alcohols [ArCHdouble bond; length as m-dashCHCH(OH)CF3] under the action of anhydrous FeCl3 was found to give fluorinated indanes in 62–90% yields via the formation of intermediate allyl cations. Reactions of CF3-allyl alcohols with arenes (Ar′H) led to CF3-alkenes [Ar(Ar′)CHCHdouble bond; length as m-dashCHCF3] in 48–75% yields. The mechanisms of the transformations are discussed.