We have investigated an oxygen gas-pulsed plasma in conjunction with the enhancement of atomic oxygen radicalO*flux and its application. The measured meanO*flux of5.9×1015atoms/cm2 sfrom the gas-pulsed plasma with a duty cycle of 50&percent; (periodically opened for 0.3 s and closed for 0.3 s) at 32 sccm is 1.6 times enhanced compared to that of a continuous wave plasma and is in good agreement with the increment obtained with the time averaged value of transient optical emission profiles ofO*at777.6 nm. The generation of a higherO*flux was interpreted by the mitigation of a recombinative reaction process through the interruption of gas flow injections in the gas pulsed plasma. As a preliminary application, an increase in critical temperature of superconductingYBa2Cu3O7−xthin films was achieved by the gas-pulsed plasma oxidation with a duty cycle of 50&percent;. ©1997 American Institute of Physics.