Immobilized triflate derivatives (La(OTf)(3), AgOTf, tert-butyldimethylsilyltrifluoro-methanesulfonate), and triflic acid were found to be effective in the alkylation of phenol and naphthols with tert-butanol. The acidic strength and type of acidity (Lewis or Bronsted) are key factors controlling the conversion and product distribution.