The dissociation of I2 molecules at the optical axis of a supersonic chemical oxygen-iodine laser (COIL) was studied experimentally as a function of I2 flow rate. The measurements revealed that the number of consumed O2(1Δ) molecules per dissociated I 2 molecule depends on the experimental conditions: it is 4.2 ±0.4 for typical conditions and I2 densities applied for the operation of the COIL, but increases at lower I2 densities. In addition, a new method for dissociating I2 prior to its mixing with O2(1Δ) and thus reducing the loss of O 2(1Δ) is reported. The method is based on applying corona/glow electrical discharge in the transonic section of the secondary flow in the COIL supersonic nozzle. 1.7% of I2 is dissociated by the discharge resulting in 70% power enhancement at rather high I2/O 2 ratio, 1.6%, close to the optimal value (∼ 2.5%) for operation of COILs with supersonic mixing.