Diglychie hydrobromide is orthorhombic, space group P 2 1 2 1 2 1 . The unit cell has edges a = 8.21 Å, b = 18.42, c = 5.40, and contains four molecules of composition 2( C 2 H 5 NO 2 ) · HBr . Intensity data were gathered by means of the D awton method, using precession and W eissenberg photographs. The bromine atom locations were determined from P atterson projections, and the structure was solved by the heavy atom method. It was refined by four sets of difference syntheses. The structure contains two non-equivalent, nearly planar molecular groups of [unk] which are held together by hydrogen and van der W aals ' bonds.