Abstract Following upon a preliminary examination of the dihydrogen phosphates of potassium and ammonium by O. Hassel‡ the structure of KH2PO4 has been examined in detail by S. B. Hendricks.§ Laue, rotation and powder photographs were employed in this last investigation, and, in the case of the rotation photographs, a correction was applied to the intensities of the registered photographic spots to allow for the different degree of absorption of the incident radiation due to the varied orientation of the reflecting planes.