This project seeks to develop the necessary theoretical and experimental understanding, expertise and techniques to test physical quantum random number generators. The importance of quantum random number generators is widely acknowledged, as is the size of the market for component level devices that are small and cheap enough to be incorporated into small systems, e.g. mobile phones; for authentication purposes e.g. in the Internet of Things; and as essential components in quantum communication systems. Authoritative accreditation of the output is an outstanding issue for QRNGs. Current tests are based on numerical analysis of the output sequence, which cannot provide a confident bound on the degree of randomness. Stronger certification is possible for physical QRNGs (PQRNGs), since the physical process used to create the output sequence can be theoretically analysed and physically tested. The developed approach will be applied to one or two selected implementations, including a commercial device (adapted to facilitate interrogation).