The breakdown of oxygen in a dc electric field is studied. A high concentra
tion of oxygen molecules in the a(1)Delta(g) excited state is obtained in a
purely chemical reactor. A decrease in the breakdown voltage at degrees of
excitation exceeding 50% is observed. The theoretical decrement in the bre
akdown voltage obtained by solving the Boltzmann equation is in good agreem
ent with the experimental data. (C) 2000 MAIK "Nauka/lnterperiodica".