We studied, at the air-water interface, monolayers of bowl-shaped liquid crystals (BLC). These compounds exhibit columnar mesophases. They consist of an either rigid or flexible central core to which are attached several hydrophobic aliphatic chains. We investigate experimentally in this work, using different technique (mainly Langmuir balance and displacement current technique), the molecular organization of these compounds at the air-water interface and we discuss some of their structural aspects. We show also the flexibility of the central core in the case of the 4BCD and discuss its effect on the structure of the monomolecular films.