Abstract Background: The role of oxygen therapy to palliate dyspnoea is controversial. Without a clear evidence base oxygen is commonly prescribed, sometimes to the detriment of patients. This use of oxygen appears to be an entrenched culture, the roots of which remain obscure. Aim: To explore healthcare professionals’ perceptions of oxygen therapy in palliative care. Design: Interpretative phenomenological analysis study utilising semi-structured interviews to explore beliefs and behaviours of healthcare professionals regarding palliative oxygen therapy. Data were recorded, transcribed and analysed using interpretative phenomenological analysis. Setting/participants: A total of 34 healthcare professionals, including doctors, nurses, pharmacists and paramedics in the United Kingdom, who were involved in prescribing, or administering, oxygen therapy to palliate dyspnoea. Results: Most healthcare professionals in this study were well informed about oxygen therapy; all recognised the role of oxygen in palliative care setting as important. The overarching theme of compassion identified sub-themes of ‘comfort’, ‘do anything and everything’ and ‘family benefit’. However, the use of oxygen in the palliative care setting was not without its dilemmas, as additional sub-themes of ‘controversy’, ‘doubt’ and ‘dependency’ illustrated. Conclusion: Findings suggest that oxygen therapy in palliative care poses an on-going dilemma for healthcare professionals striving to provide optimum care. It seems patients and families often expect and welcome oxygen, but the perception of oxygen as a solution to dyspnoea can conflict with healthcare professionals’ own doubt and experiences. There appears to be an emotional cost associated with this dilemma and the choices that need to be made.