Operation of an UV preionized pulser sustainer TEA CO2laser with a discharge volume of 45 cc is described. The laser could provide 522 mJ optical pulses of 6 &mgr;s duration (full width at half‐ maximum) with 12% efficiency for a 1:1:6 (CO2:N2:He) gas mixture at one atmospheric pressure. To the best of our knowledge, this is the maximum energy per pulse reported so far for an all solid state switched TEA CO2laser with this efficiency. ©1995 American Institute of Physics.