X-ray Reflectivity (XR) and grazing angles of incidence X-ray diffraction (GIXD) were conducted to determine the structure of Cr8O4(O2CPh)(16) Langmuir films at the air/water interface at various surface pressures pi. The molecular area versus pressure, pi -A isotherm, reflectivity, and GIXD variation (width and peak position) with compression, all imply the formation of a homogeneous monolayer at very low surface pressures. The film is disordered with a liquidlike or glassy structure factor at all pressures, with correlation lengths that extend over a few molecular distances. The liquidlike state of the monolayer and an incomplete formation of a second layer have implications on the quality of transferred Langmuir-Blodgett films.