New effective methods were developed for the preparation of useful electrophilic trifluoromethylating agents, S-(trifluoromethyl)dibenzothiophenium tetrafluoroborate (3) and triflate (4) and S-(trifluoromethyl)dibenzothiophenium-3-sulfonate (6). Thus, salts 3 and 4 were produced by the intramolecular cyclization of sulfoxide 1 with fuming sulfuric acid, followed by the counteranion replacement reaction of the intermediate (2) with sodium tetrafluoroborate and triflate, and salt 6 was directly produced from 1 by treatment with excess fuming sulfuric acid. Useful preparative methods for 1 were also described.