Ammonia has been identified as a sustainable fuel for transport and power applications. Similar to hydrogen, ammonia is a synthetic product that can be obtained either from fossil fuels, biomass or other renewable sources. Since the 1960's, considerable research has taken place to develop systems capable of burning the material in gas turbines. However, it is not until recently, that interest in ammonia has regained some momentum in the energy agenda as it is a carbon free carrier and offers an energy density higher than compressed hydrogen. Therefore, this work examines combustion stability and emissions from gaseous ammonia blended with methane or hydrogen in gas turbines. Experiments were carried out in a High Pressure Combustion Rig under atmospheric conditions employing a bespoke generic swirl burner. OH* Chemiluminescense was used for all trials to determine reactivity of the radical. Emissions were measured and correlated to equilibrium calculations using GASEQ. Results show that efficient combustion can be achieved with high power but at very narrow equivalence ratios using both hydrogen and methane blends. Moreover, low concentrations of OH radicals are observed at high hydrogen content, probably as a consequence of the high NH2 production.