Physicochemical characterization of (S)-4-[1-(2,3-dimethylphenyl)ethyl]-3H-imidazole HCl in solution as well as the solid state has been done using single-crystal X-ray crystallography, 1 H and 13 C NMR, IR and mass spectrometry. The single-crystal structure, as well as Hirshfeld surface analysis, of the S-enantiomer is compared with the racemate, as well as the polymorph of the racemate. The decomposition kinetics of the S-enantiomer have been studied using thermogravimetric analysis and a differential scanning calorimetric investigation. The study was done to contribute to understanding the properties of the drug at a molecular level, thus providing tools to develop novel formulations of the drug.