4-[(3-Acetylphenyl)amino]-2-methylidene-4-oxobutanoic acid (1) is synthesized by a ring opening reaction of itaconic anhydride with 3-aminoacetophenone and characterized by FT-IR, H-1 NMR, UV-Vis, TGA, DTA, and single crystal X-ray diffraction. The crystal of 1 belongs to triclinic unit cell in the P-1 space group with the unit cell dimensions a = 4.9485(3), b = 5.3614(6), c = 22.457(2) angstrom, alpha = 88.295(8), beta = 89.379(7), gamma = 84.495(7), and Z = 2 The crystal structure is solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R-value of 0.0467 for 1623 observed reflections. Intermolecular NH horizontal ellipsis O and OH horizontal ellipsis O hydrogen bonds links the molecules into chains along [010] direction. In addition the thermal stability of the 1 is determined by using DTA, TGA analysis, and wavelength absorption at lambda(max) = 297nm is determined by UV-Vis spectrophotometer.