This research shows the development of a complete novel medical device capable of achieving haemostasis of upper gastrointestinal bleeding. A novel transmission structure has been designed and tested which includes a hollow central channel running through the inner conductor allowing for the delivery of fluid or introduction of clinical tools such as forceps, biopsy graspers or needles alongside the delivery of microwave energy. To facilitate the initial testing and subsequent clinical usage of the cable; multiple transformer structures were considered and developed both for the delivery of microwave and radio frequency energy. These allowed for the testing and characterisation of multiple cable prototypes developed throughout this research. In order to achieve the required clinical effect, namely coagulation of bleeding vessels, a solution which allowed optimal delivery of energy from the cable structure into the tissue at the treatment site was developed. Radiative tip prototypes were simulated, manufactured and tested to show matching between the lower impedance cable and the higher impedance tissue. Finally a number of complete devices were assembled and tested using microwave test equipment, on bench tissue testing using porcine liver and also during a pre-clinical investigation held at Northwick Park Institute for Medical Research, one of the UK’s leading charity-based independent Medical Research Institutes. Clinician feedback and histological analysis is presented within and show successful coagulation of multiple simulated oesophageal bleeds.