This review article focuses on the application of spectroscopic methods for the structural analysis of chitin and chitosan, two versatile biopolymers with a wide range of applications in medicine, agriculture, and the food industry. Chitin, the second most abundant natural polymer, is derived from crustacean shells and exhibits unique chemical, physicochemical, and biological properties. Chitosan, a derivative of chitin, is formed by deacetylation and has similar properties but is more soluble in water. The presence of reactive functional groups and the polysaccharide nature of these biopolymers enable them to undergo diverse chemical modifications. The review covers several spectroscopic techniques, including X-ray spectroscopy, infrared (IR) spectroscopy, UV-Vis-spectroscopy, mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. These techniques are essential for determining molecular structures, monitoring reactions, and controlling the purity of chitin, chitosan, and their derivatives. X-ray spectroscopy, particularly X-ray diffraction (XRD), is a versatile tool for characterizing the electronic and geometric structures of materials. It has been used to study the polymorphs of chitin and chitosan, their crystallinity, and the effects of various parameters such as degree of N-acetylation and molecular weight on their structure. IR spectroscopy, especially Fourier-transform infrared (FTIR) spectroscopy, is widely used to identify bond types and determine the allomorphs of chitin. UV-Vis-spectroscopy, MS, and NMR spectroscopy are also discussed for their roles in the structural analysis and physicochemical characterization of these compounds. The article highlights the importance of these spectroscopic methods in understanding the structure-property relationships of chitin and chitosan, which is crucial for their applications in various industries.This review article focuses on the application of spectroscopic methods for the structural analysis of chitin and chitosan, two versatile biopolymers with a wide range of applications in medicine, agriculture, and the food industry. Chitin, the second most abundant natural polymer, is derived from crustacean shells and exhibits unique chemical, physicochemical, and biological properties. Chitosan, a derivative of chitin, is formed by deacetylation and has similar properties but is more soluble in water. The presence of reactive functional groups and the polysaccharide nature of these biopolymers enable them to undergo diverse chemical modifications. The review covers several spectroscopic techniques, including X-ray spectroscopy, infrared (IR) spectroscopy, UV-Vis-spectroscopy, mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. These techniques are essential for determining molecular structures, monitoring reactions, and controlling the purity of chitin, chitosan, and their derivatives. X-ray spectroscopy, particularly X-ray diffraction (XRD), is a versatile tool for characterizing the electronic and geometric structures of materials. It has been used to study the polymorphs of chitin and chitosan, their crystallinity, and the effects of various parameters such as degree of N-acetylation and molecular weight on their structure. IR spectroscopy, especially Fourier-transform infrared (FTIR) spectroscopy, is widely used to identify bond types and determine the allomorphs of chitin. UV-Vis-spectroscopy, MS, and NMR spectroscopy are also discussed for their roles in the structural analysis and physicochemical characterization of these compounds. The article highlights the importance of these spectroscopic methods in understanding the structure-property relationships of chitin and chitosan, which is crucial for their applications in various industries.