The crystal structures of three xylazine hydrochloride [N-(2,6-dimethylphenyl)-5,6-dihydro-4H-1,3-thiaz-2-amine hydrochloride] polymorphs A, Z and X have been solved from powder diffraction data and refined using Rietveld refinement. Data were obtained with Cu Kα radiation. All polymorphs were found to have structures with Z' = 1 and Z = 4. All the structures determined contained strong hydrogen bonds between the amino groups and chloride anions. The crystal structures of forms A and X featured π-π stacking interactions.
Keywords: polymorphism; powder diffraction; xylazine hydrochloride.