The X-ray crystal structure of 6,7-dihydro-5a,7a,13,14-tetraaza-pentaphene-5,8-dione, a potential antiproliferative agent against A2058 melanoma cells, was determined. The compound crystallizes in the monoclinic space group P2/c with specific cell parameters and refinement values. The crystal structure reveals intermolecular C_Arom–H–O hydrogen bonds forming trimers. The compound exhibited significant antiproliferative activity, inhibiting cell growth by 40.2 ± 3.3% and 6.9 ± 3.5% at 10 and 1 μM, respectively. The structure was characterized using X-ray diffraction, and the crystallographic data were deposited in the Cambridge Crystallographic Data Centre.The X-ray crystal structure of 6,7-dihydro-5a,7a,13,14-tetraaza-pentaphene-5,8-dione, a potential antiproliferative agent against A2058 melanoma cells, was determined. The compound crystallizes in the monoclinic space group P2/c with specific cell parameters and refinement values. The crystal structure reveals intermolecular C_Arom–H–O hydrogen bonds forming trimers. The compound exhibited significant antiproliferative activity, inhibiting cell growth by 40.2 ± 3.3% and 6.9 ± 3.5% at 10 and 1 μM, respectively. The structure was characterized using X-ray diffraction, and the crystallographic data were deposited in the Cambridge Crystallographic Data Centre.