The solid state 2-chloro-4-nitrobenzoic acid is known today as an active ingredient in the medicalpharmaceutic field, used in therapy for immunodeficiency diseases, including HIV infection [1, 2]. The aim of this work is to study the crystallization of dimethylethanolamine salt of 2-chloro-4nitrobenzoate, to identify and characterize the various solid forms (polymorphs, hydrates and solvates) formation. Slow crystallization from different solvents (acetone, diethylether, acetonitrile) under controlled conditions was employed to prepare various crystalline forms. Three crystal forms (an anhydrate and two monohydrates) of dimethylethanolamine salt of 2-chloro-4-nitrobenzoate were identified and characterized by single crystal X-ray diffraction to better understand the hydrogen bonding interactions and investigate molecular packing in crystalline forms. Thus, the anhydrate form (1) crystalized in the orthorhombic space group Pna21 with cell parameters a = 24.6920(9) Å, b = 8.9437(4) Å, c = 6.1887(3) Å, Z = 4, the monohydrate obtained from diethylether (2) crystalized in monoclinic space group P21/n with cell parameters a = 12.1759(5) Å, b = 6.0702(3) Å, c = 30.8654(14) Å, β = 92.858(4)°, Z = 4 and instead the monohydrate obtained from acetonitrile (3) crystalized in triclinic space group P-1 with cell parameters a = 5.6126(6) Å, b = 10.2223(9) Å, c = 12.4751(11) Å, α = 93.762(7)°, β = 92.858(4)°, γ = 91.432(8)°, Z = 2. The salts units of 1, 2 in crystal are held together by one charge-assisted N–H…O hydrogen bond and one normal O–H…O hydrogen bond wich generate the supramolecular synthons R22(9), while in 3 the cations and anions are held together by one charge-assisted N–H…O hydrogen bond. The influence on crystal packing of O–H…O hydrogen bond formed by involving solvation molecules as well as of C–H…O and C–H…Cl hydrogen bonds will be discussed in this study