The present invention provides an improved process for obtaining alpha (a)-form crystals of Mirabegron (I) comprising crystallizing solid compound (I) (as described herein) from water. The present invention provides an improved process for obtaining alpha (a)-form crystals of Mirabegron (I) comprising the steps of (a) suspending beta (p)-form crystals of Mirabegron in water (b) heating the reaction mixture of step (a) (c) cooling the reaction mixture of step (b) (d) isolating alpha (a)-form crystals of Mirabegron. The invention also provides a novel crystalline Form-MP of the intermediate compound (R)-2-((4-nitrophenethyl) amino)- 1-phenylethanol (II).
