A prototype flameless oxidation (FLOX) gas turbine combustor has been investigated experimentally and numerically. The combustor was operated with various Low Calorific Value gases. At the outlet main component and emission measurements (CO and NO) have been performed. The influence of several parameters (i.e., fuel composition, outlet temperature, and nozzle diameter) on the emissions have been investigated. Ultralow emissions (single digit) have been achieved. Moreover, axial temperature profiles in the combustion chamber have been measured with a suction pyrometer. The combustor has been simulated with a commercial CFD code (FLUENT 6.3) to gain insight in the combustion characteristics. Using the Eddy Dissipation Concept model for turbulence-chemistry interaction in combination with the Reynolds Stress model for turbulence and two different chemistry mechanisms, the measured temperature profiles have been reasonably well reproduced. In postprocessing mode different NO formation paths have been studied.