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Reaction of cyclic ketones 2–6 and imines 15–17 in HF/SbF5 in presence of CCl4 yield hydroxy or fluoroderivatives, hydride abstraction occurring at a site located far from the functional group. Whereas ketones 2–5 yield only hydroxy derivatives, through cyclic carboxonium ion, imines 15, 16 N-protonated in the media conditions give only fluoroderivatives 18, 19, respectively, after quenching with HF–pyridine. Ring contraction is operative when starting from large membered ring ketones 24 and 25, and imine 26, leading to a mixture of hydroxy or fluoro cyclohexanones and/or cycloheptanones. [Copyright &y& Elsevier]