The use of ammonia as an alternative fuel in gas turbines or spark-ignition engines have already been tested. As high pressures and temperatures are reached in these industrial combustors, it is necessary to obtain a robust detailed kinetic mechanism able to predict laminar flame speed for ammonia at these conditions. In order to assess the validity of such a kinetic mechanism, reliable targets are mandatory. The present study focusses on measuring flame speeds at elevated thermodynamic conditions for different equivalence ratios in a constant volume spherical chamber. This new methodology allows to provide 3D maps of S L = f (p, T) for different equivalence ratios. A literature study was also performed to evaluate and select the most recent kinetic mechanisms for ammonia combustion under these extreme conditions. Sensitivity analyses highlighting the key reactions for two of the most promising mechanisms has been performed. Interestingly, it turns out that, although they are both in good agreement with our new experimental data, the sensitive reactions are not all the same, indicating the chemistry of ammonia needs further investigations.