Oxygen therapy has become a major tool for infants with acute and chronic respiratory failure. Appropriate goals when prescribing supplemental oxygen are reduction and prevention of hypoxemia, prevention and treatment of pulmonary hypertension and decrease in respiratory and cardiac overload. This is commonplace in the acute setting and is also becoming widespread in chronic pathologies. However, there is a lack of consensus on many fundamental issues, such as appropriate indications, desirable targets and outcome measures amongst centres, reflecting a variety of clinical practices. The Techniques Group of the Spanish Society of Pediatric Pneumology undertook to design recommendations for a rational approach to oxygen therapy, reviewing the existing literature in order to establish its indications, benefits and potential risks as well as its cost-effectivenes. General aspects of oxygen treatment are reviewed including physiological mechanisms, indications, delivery systems and assessment methods. Management of patients on home oxygen therapy is also addressed with discussion of benefits and potential risks of supplemental oxygen use.