Valence electronic excitation spectra are calculated for the H2O***Cl2 dimer using state-of-the art ab initio potentials for both the ground and the valence excited states, a basis set calculation of the ground state nuclear wave funtion, and a wave packet analysis to simulate the dynamics on the excited state surface. The peak of the H2O***Cl2 dimer spectrum is blue-shifted by 1250 cm−1 from that of the free Cl2 molecule. This is less than the value previously estimated from vertical excitation energies but still significantly more than the blue shift in aqueous solution and clathrate−hydrate solid. Seventy percent of the blue shift is attributed to ground state stabilization, the rest to excited state repulsion. Spin−orbit effects are found to be small for this dimer. Homogeneous broadening is found to be slightly smaller for the dimer than for the free Cl2. The reflection principle and spectrator model approximations were tested and found to be quite satisfactory. This is promising for an eventual simulation of the condensed phase spectra.