Despite numerous potential industrial application of ammonia (NH3 ), the risk of detonation in NH3 -based mixtures has not been characterized in details. In the present study, the velocity and cell size of detonation propagating in NH3-O2 and NH3-N2O mixtures have been measured. Mixtures containing nitrous oxide as an oxidant demonstrated higher sensitivity to detonation than mixtures containing oxygen. The semi-empirical correlation from Ng was employed to predict the detonation cell size. It provided reasonable predictions with maximum deviation below a factor of 2. The detonation chemical structure was characterized using steady one-dimensional ZND simulations. For mixtures containing nitrous oxide, the production of OH radical is controlled by the reaction N2O+H=N2+OH whereas for mixtures containing O2, the controlling reaction is H+O2=O+OH. Consistent with the experimental soot foils, the calculated stability parameters enable classifying the studied ammonia-based mixtures as highly unstable.