Three mixtures of the endohedral metallofullerene Dy@C-82 and arachidic acid (AA) with different molar ratios have been investigated at the air-water interface in the presence of Cd2+ in the aqueous subphase. Compared with the pure Dy@C-82, the Langmuir-Blodgett (LB) films of the mixtures with AA were easily fabricated by the vertical dipping method. The structural characteristics of these films were studied by UV-Vis spectroscopy, atomic force microscopy, and X-ray diffraction measurements. When the molar ratio AA:Dy@C82 exceeds 2:1, the corresponding LB films exhibit an ordered layer structure.