Background: Patients with respiratory disorders such as chronic obstructive pulmonary disease (COPD) are prescribed oxygen therapy, but frequently fail to use it as intended and therefore do not receive the associated health benefits. Many of the reasons for this non adherence to therapy relate to the design of the equipment currently provided. We have designed and developed a novel system for portable oxygen delivery to overcome this problem. Method of Approach: There were five complementary workpackages (user involvement and exploratory work; ultra lightweight cylinder technology; embedded valve regulator technology; patient-driven system design; regulatory design & manufacturing review). Each had specific deliverables supporting the end point of the program, i.e., to have a fully functioning prototype oxygen delivery system that had been designed and evaluated with maximum input from end users. Results: Patients primarily wanted a lightweight, long lasting, reliable, unobtrusive and ergonomically designed system with simple controls. To provide this, we have developed a new full wrap composite cylinder that has achieved weight savings of ∼12% over a comparative composite cylinder, or a doubling in cylinder design life. We have developed a totally new concept in valve regulator technology, conferring significant reductions in weight and space envelope. We have addressed form factor, flow dial design and flow setting indicator design to improve the ergonomics and esthetics of the system. The developed prototype system weighs 1.7 kg when full, is 34.2 cm in height and 8.5–8.7 cm in diameter, and is capable of 8 h operation at a flow rate of 2 liters per minute, using a standard conserver. Conclusions: Throughout this project, a significant amount of time was invested in establishing the views and perceptions of potential end-users of the new system. This has ensured that their views informed the design and development process. By combining novel cylinder technology with revolutionary valve technology (SmartFlow) we have been able to design an ultra-light cylinder oxygen system (IOS® ) with accurate, reliable and stable flow. The weight reduction combined with the new easy-to-read gauge and user-friendly controls should improve patient confidence in the system and result in increased adherence to therapy.