1. INTRODUCTIONCrystallization is an essential technique in pharmaceutical manufacturing since most active pharmaceutical ingredients (APIs) are available in solid form1. It plays an important role in marketing, manufacturing and in particular in the interaction with excipients in the crystalline state2. Physical properties of active pharmaceutical ingredients such as crystal form, morphology, and particle size distribution will strongly affect the solubility and bioavailability of a solid dosage form. (Table 1) 3. The crystallization process, particularly crystallization from solution, is used as a separation and purification technique and in the production of solid dosage forms3,4. Knowledge of crystal structure allows the crystal engineer to know and manipulate the chemistry of the crystal in order to optimize its exact characteristics. 3. Additionally, the chemical and physical properties of a material are dictated by the crystallization process. Crystal properties such as: particle size, shape, surface characteristics, purity and defect structure, as well as thermodynamic and mechanical properties3 will be affected by even minor changes in crystallization conditions.5.1.1 CrystalA crystal is defined as a solid form that contains a very high degree of internal three-dimensional order of the component atoms, molecules, and ions2. The crystal structure of atoms and molecules has a unique arrangement, which leads to the regular repetition of interatomic distances within the material4. The shape of a crystal is a reflection of its internal structure on the atomic scale. The faces of a crystal are labeled relative to the crystal's axes. Each face has a set of three integers (h, k, l), known as Mill...... middle of paper ......ed to provide enough data to determine the unit cell and the crystal system30- 35. Once the optimal data collection is automatically calculated by the control system, a complete set of images is recorded, which will provide the complete set of data required for structure determination.35.4. 2 X-ray powder diffractionPowder diffraction is used for the identification of unknown materials. For a powder, the spots observed in single crystal patterns are spread out in rings of powder. In X-ray powder diffraction, it is not necessary to move the sample in the powder diffractometer, because for each Bragg crystal plane, some crystallites will be statistically oriented correctly34. All necessary information that requires identification of a phase by comparison with a database of models from known materials is provided when a single radial scan is displayed35.