The single-frequency two-level (SFTL) generation model was applied to predict the power extraction efficiency in electrically driven oxygen-iodine laser (EOIL). The analysis of the calculated and published experimental data showed that power extraction from the cw EOIL is limited by the rate of energy transfer from singlet oxygen molecules O 2 ( 1 Δ) to iodine atoms I( 2 P 3/2 ) and about half of the produced singlet oxygen molecules were carried out from the resonator. To increase power extraction efficiency it will be necessary to substantially extend concentrations of singlet oxygen molecules and iodine atoms in the active medium of EOIL.