The structure and the electronic properties of graphite monofluoride (CF)n have been studied within the framework of the density-functional technique, using nonlocal ionic pseudopotentials and a large number of plane waves. The chair conformation is shown to be energetically favored with respect to the boat conformation by 0.145 eV per CF unit. The transition between these two states has been investigated: the boat conformation is metastable, with an estimation of the transition barrier on the order of 2.72 eV. This indicates that the material actually synthesized could depend on the kinetics of the intercalation or could as well be a mixing of both conformations. The equilibrium geometries are compared with experimental data. We also present the valence charge density and the band structure of the chair conformation.