The crystal and molecular structures of iminodiacetic acid hydrochloride, C4H7NO4. HC1, and iminodiacetic acid hydrobromide, C4H7NO4.HBr, have been determined by a symbolic addition method with three-dimensional single crystal X-ray data obtained on a diffractometer. The compounds are isostructural, crystallizing in the orthorhombic space group Pmmn with Z= 2. The unit-cell dimensions are a= 12.4101, b= 5.7349, c=5.1280 A~ and a= 12.8150, b= 5.8705, e=5.0870/~ for the chloride and bromide respectively. Positively charged iminodiacetic acid ions are connected by hydrogen bonds via the halide ions and zigzag layers are formed. These layers are stacked in the c direction and the forces between the layers are of van der Waals type.