A new Z = 8, Z' = 2 polymoroph of 4-oxo-4-phenylbutanoic (β-benzoylpropionic) acid, C₁₀H₁₀O₃, was obtained. The previously published two polymorphs with CCDC codes VERMAG and VERMAG01 crystallize with Z = 4, Z' = 1 in monoclinic space groups P2₁/c [a = 15.071(10), b = 5.435(9), c = 16.058(10), β = 129.57(10)] and P2₁/n [a = 12.728(6), b = 5.200(3), c = 14.426(6), β = 111.33(3)], respectively. Reported herein polymorph crystallizes in the monoclinic space group P2₁/c and has significant larger cell volume of 1754.51 ų [a = 15.2673(6), b = 5.2028(2), c = 22.3063(8), β = 98.0217(7)]. Structurally, new polymoroph differs from two known other slightly (RMSD of about 0.112-0.183 Å). All polymorphs contain dimers of molecules bounded by intermolecular hydrogen bonds leaving carbonyl groups at position 4 unaffected.