The synthesis, crystal structure analysis and characterisation of 5-[thiazol-2-yldiazenyl]pyrimidine-2,4,6(1H,3H,5H)-trione are reported. This dye was characterised by ultraviolet-visible, Fourier Transform-infrared, proton nuclear magnetic resonance spectroscopy, mass spectrometry techniques and elemental analysis. Both the effects of pH value and solvent polarity upon the absorption properties of the dye have been presented. In addition, the structure of the dye has been determined by a single crystal X-ray diffraction method. The dye was triclinic in P-1 with a = 8.2419(2) angstrom, b = 10.6225(3) angstrom, c = 12.5106(3) angstrom, alpha = 90.543(1)degrees, beta = 102.79(3)degrees, gamma = 103.858(1)degrees, V = 1035.26(5) angstrom(3), D-calc = 1.634 g/cm(3) and Z = 2. The asymmetric unit contains two crystallographically independent C7H5N5O3S molecules, alongside one half of the solvent C2H6O2 molecule. In the crystal structure, intramolecular N-H...N and intermolecular N-H...N, N-H...O, O-H...N, C-H...O and C-H...N hydrogen bonds link the molecules to form a supramolecular network in which they seem to be effective in the stabilisation of the structure.