An approach for the construction of diffusion-limited size-selective sensors' is described based on the self-assembly of cyclic peptides into tubular channels in organosulfur self-assembled monolayers on gold films. An eight-residue cyclic peptide of alternating units of D-Leu and L-Trp amino acid residues was incorporated into monolayers of dodecanethiol and octadecyl sulfide and shown to adopt highly oriented tubular structures under specified adsorption conditions. The structural properties of monolayer-supported peptide nanotubes have been analyzed by grazing angle FTIR spectroscopy and their selective ion transport activities by cyclic voltammetry and impedance spectroscopy.