We have synthesized novel heptaalkyl amphiphiles, Heptopus(12,12), Heptopus(12,14), and Heptopus(12,14), that have six identical outer alkyl chains (C-12, C-14, or C-16) and a single inner alkyl chain (C-12). Their monolayer properties were investigated by pi-A isotherm measurement and atomic force microscopy (AFM). Limiting areas in their isotherms are 1.54, 1.38, and 1.40 nm(2) for Heptopus(12,12), Heptopus(12,14), and Heptopus(12,16), respectively, suggesting formation of close-packed condensed phases. An AFM observation of a monolayer of Heptopus(12,12) transferred onto a mica showed hexagonal packing of its alkyl chains. However, the outer and inner chains were not distinguishable. These results indicate that further elaboration on the molecular design of Heptopus is required to create novel two-dimensional molecular organization.