Octadecyl substituted amphiphiles of the four nucleobases, adenine, cytosine, guaine, and thymine (C-18-Ade, C-18-Cyt C-18-Gua, and C-18-Thy, respectively), were prepared. Binary mixtures of these amphiphiles were spread on water surface as monolayer assemblies. Pressure-area isotherms of all pairwise combination of the nucleobase amphiphiles indicate that the Watson-Crick type base-pairings and base-stacking can stabilize monolayers at the air-water interface. Unexpected stabilization was observed in the combination of C-18-Gua and C-18-Thy, which resembles a "wobble" pair in RNA. Langmuir-Blodgett films were prepared on gold substrates for FT-IR measurement of the complementary hydrogen bonding between the nucleobase amphiphiles.