This paper reports the first results of microdischarge studies performed using real time imaging of the plasma electrolytic oxidation process. It is shown that small microdischarges with a cross-sectional area of approximately 0.02 mm 2 dominate throughout the oxidation process. With the oxide coating growth, the percentage of large (area 0.37 mm 2 ) and extra-large microdischarges (area >0.87 mm 2 ) in the total microdischarge population increases from 0 to 8% and 4%, respectively, at the end point. At the same time the microdischarge current density falls from 50 to 18 kAm - 2 , due to the increase in total testpiece area exposed to microdischarges from 3 to 6%. The microdischarge contribution to coating growth is evaluated to be in the range of 8-10 nm per a microdischarge event.