Ru4+ ions in Li2RuO3 are on a bipartite lattice and have an orbital degeneracy. The four electrons of the magnetic Ru4+ ions in the threefold-orbitally degenerate t2g manifold are coupled into a spin S= 1 state. An usual phase transition with an orbitally dimerized spin-singlet groud state is observed in Li2RuO3 below 540 K, where the crystal symmetry also exhibits a transition from C2/m monoclinic to P21/m monoclinic, magnetic susceptibility exhibits a sharp drop and the electrical resistivity shows a jump on cooling. We propose to investigate the magnetic excitations of Li2RuO3 using inelastic neutron scattering measurements on MERLIN. We expect to determine the spin gap, to search for excitations from the orbitally dimerized state and to test the models of Ru-Ru coupling and Ru-Ru bonding in Li2RuO3.