Theoretical studies of monolanthanum carbides, LaCn for n = 2-6, are presented. The fan structures were found as ground states in most cases studied. The computed enthalpies of formation of LaCn and atomization energies of these species an close to the corresponding experimental data. The agreement is even closer when experimental Gibbs energy functions are corrected using theoretical ground state structures and partition functions. The La-C bond is strongly ionic due to electronic charge transfer from lanthanum to carbon atoms.