Layered ruthenates exhibit a large variety of interesting phenomena reaching from unconventional superconductivity in Sr2RuO4 to a Mott-insulating state in Ca2RuO4 and a metamagnetic transition which is associated with quantum-critical behaviour.The theoretical analysis of the electronic structure of Ca2RuO4 is quite complex due to the fact that there are four electrons per Ru site which occupy the three t2g orbitals in a low-symmetry structure. As the orbital moment is not fully quenched there is sizeable spin-orbit coupling. The most recently published theory tries to bridge the Mott state in Ca2RuO4 with that in iridates (like Sr2IrO4) where spin orbit coupling is the essential interaction to determine the magnetic ground state.Ca2RuO4 seems to be very well suited for studying the impact of strong spin-orbit coupling on a Mott insulator in close relation to the enormous efforts recently made on iridates. Inelastic neutron scattering studies are required to analyze the magnon dispersion in Ca2RuO4 which is supposed to clarify the magnetic ground state.