Long-term oxygen therapy (LTOT) is indicated in stage-IV COPD. It increases survival when used 24h/24, ideally, and at least 15h/24. There is no indication for prescribing nocturnal oxygen therapy without de LTOT. Ambulatory oxygen therapy is indicated in patients with COPD who benefit from LTOT in case of significant exercise-induced desaturation. In that regard, recent technologies allow to provide patients with small-size, stand-alone and portable oxygen units. Non-invasive ventilation (NIV) is a type of mechanical ventilation administered through a mouthpiece, a nasal mask or a facial mask. It should not be confused with continuous positive airway pressure (CPAP), indicated in the treatment of obstructive sleep apnea, which does not improve alveolar ventilation in hypercapnic patients. In patients with COPD, long-term NIV does not provide any benefits in terms of survival instead, it improves arterial gasometry, clinical symptoms, quality of life and the frequency of severe exacerbations.