The microstructure of high density amorphous carbon materials prepared by direct and filtered cathodic arc deposition was studied by electron diffraction measurements and molecular dynamic (MD) as well as Monte-Carlo (MC) modelling. The MD simulation, performed by quenching of a liquid, is based on a semiempirical density functional (DF) approach. The MC simulation uses a modified WWW algorithm and an empirical classical description of the atomic interactions. By comparison of the experimental results with theoretically simulated diffraction data, the atomic structure and chemical bonding in the a-C films are analysed and structure property correlations are discussed.