Mirabegron, (C 21 H 24 N 4 O 2 S), is a β 3 -adrenoceptor agonist approved in Japan, the USA, Canada and Europe, for the treatment of overactive bladder symptoms. There are no entries for this important active pharmaceutical ingredient in the Cambridge Structural Database or the Powder Diffraction File-4/Organics database. In this contribution, the powder diffraction pattern of Mirabegron, an unreported phase, are presented with a study by spectroscopy methods (Fourier-transform infrared spectroscopy [FT-IR] and RAMAN) and thermal analysis (thermogravimetric analysis [TGA]-differential scanning calorimetry [DSC]).