Laser‐supported detonation waves are generated with a pulsed CO2laser with energies up to 18 J, for a duration of 25 &mgr;sec and focused on solid surfaces in air. The time‐integrated spectrum in the visible and near‐uv range is found to consist mainly of N+and O+. The temperature and the electron density in the plasma are estimated to be greater than 25 000 °K and 1.5×1017/cm3, respectively, through a theoretical analysis of the air composition.