Monolayers of the long-chain alcohol C31H63OH were spread over a water surface and deposited onto plastic holey grids. The water substrate was then vitrified by fast freezing in liquid ethane, and the samples obtained were studied by cryo-Transmission electron microscopy. Electron images and diffraction patterns, indicative of two-dimensional crystalline self-assembly, are discussed. Morphological features of the monolayer films were also obtained. The method should be of importance for the study of the structure of membranes, Langmuir-Blodgett films, and nucleation processes of two- and three-dimensional crystals.