The anharmonicity of Li+–(H2)n (n = 1, 2, and 3) complexes is studied using the vibrational self-consistent field (VSCF) approach. The H–H stretching frequency shifts of Li+–(H2)ncomplexes are calculated with the coupled-cluster method including all single and double excitations with perturbative triples (CCSD(T)) level of theory with the cc-pVTZ basis set. The calculated IR active H–H stretching frequency in Li+–H2, Li+–(H2)2 and Li+–(H2)3 is red-shifted by 121, 109, and 96–99 cm–1, respectively, relative to that of isolated H2. The calculated red shifts and their trends are in good agreement with the available experimental data.