Background Mechanical ventilation is a daily event in any ICU, using HFNO as a weaning facilitating strategy for mechanically ventilated patients after passing Spontaneous Breathing Trial (SBT) recently considered to reduce complications associated with invasive ventilation. Objectives To compare high-flow conditioned oxygen therapy versus non -invasive ventilation using continuous positive airway pressure (CPAP) for preventing post-extubation respiratory failure and reintubation in acute exacerbation of chronic obstructive pulmonary disease patients after weaning from mechanical ventilation and to follow patients for ICU and hospital lengh of stay ICU and hospital mortality. Patients and Methods This prospective randomized controlled study, including 60 patients admitted to the intensive care unit at Al- Mataria teaching hospital. Approval of the ethical committee of Al-Mataria teaching hospital was obtained before the start of patient’s recruitment. Patients who successfully extubated were equally randomized (sequential) to enter either group I or group II. Study group (I): included 30 patients subjected to high flow nasal oxygen after extubation for 24 hrs. Control group (II): included another 30 patients on non-invasive CPAP after extubation for 24 hrs. Results Our results showed lower rate of reintubation in HFNO group (n = 6) 20%, compared to NIV group(n = 7) 23. 3 %, higher PaO2 in HFNO group immediate, 2 hrs post extubation. No significant differences found regarding mortality rate between both study groups (8/30) 26. 6 % in HFNO group, while (9/30) 30 % in NIV group, p (Ns). Arterial PH was significantly lower in NIV group immediately after extubation. Conclusion HFNO compared to NIV alone showed lower rate of reintubation when used immediately after planned extubation. Patients weaned using HFNO showed higher PaO2 2hrs postextubation. HFNO compared to NIV alone didn’t affect hospital stay.