Chemical shifts and visible absorption maxima indicate that 2-phenylcyclopenta[b]-[l]-benzopyran is protonated solely on C-1 (five-membered ring) an analogous cation is probably formed from 2,4,6-triphenylcyclopenta[b]pyran. The site of protonation in cyclopenta[b]pyran and its derivatives is discussed in terms of molecular orbital theory.