Experiments in a low pressure glow discharge on gases of environmental relevance: CO2,CO y O2 are reported. We studied the various atomic processes: ionization, excitation and molecular dissociation with typical discharge parameters of p~0.6 mbar, I< 0.1 A and V~1100 Volts. We used visible and near UV spectroscopy to observe the emitted radiation on both electrodes on pure gases and hydrogen seeded mixtures. We also set up Langmuir probes in both electrodes.