Surface pressure (pi)-molecular area (A) isotherms are reported for novel films prepared from a torand (tri-n-butyldodecahydrohexaazakekulene, TBDK). The concentrations of HCl, Me4NOH, Pb(OAC)2, Pb-(ClO4)2, LiOH, KOH, and CsOH in the aqueous subphase were varied, causing pronounced changes in the pi-A curves. In the presence of Li+, Cs+, and Pb(ClO4)2 a phase transition was observed at ca. 120 angstrom2/molecule, whereas Pb(OAC)2 gave a transition at 50-60 angstrom2/molecule. The results are consistent with cation-responsive transition of the TBDK films from a horizontal bilayer to a vertical bilayer configuration at higher surface pressures.