Abstract Benzene isolated in argon or nitrogen matrix at about 5 K has been irradiated with photons of 6 eV (206.2 nm), 8.4 eV (147 nm), and 10 eV (123.6 nm) energy. In every case phosphorescence a ̃ 3B 1u → X ̃ 1A 1g and fluorescence A ̃ 1B 2u → X ̃ 1A 1g have been observed from the vibrationally relaxed states. The phosphorescence emission is still observed after the extinction of the excitation during the warming up as a thermoluminescence. The phosphorescence versus fluorescence ratio increases when passing from a nitrogen matrix to an argon matrix and as the photon energy increases. The main conclusion is that, in the condensed phase, the electronic relaxation processes leading to the emitting states are not as fast as usually assumed.