Fluorinated carbon-based thin films offer a wide range of properties for many technological applications that depend on the microstructure of the films. To gain a better understanding on the role of fluorine in the structural formation of these films, CF x systems based on graphenelike fragments were studied by first principles calculations. Generally, the F concentration determines the type of film that can be obtained. For low F concentrations (up to ∼ 5 at.%), films with fullerene-like as well as graphite-like features are expected. Larger F concentrations (≥ 10 at.%) give rise to increasingly amorphous carbon films. Further increasing the F concentration in the films leads to formation of a polymer-like microstructure. In order to aid characterization of CF x systems generated by computational methods, a statistical approach is developed.