Cinnamon (Cinnamomum cassia) has long been valued for its health-promoting properties, particularly its antioxidant, anti-inflammatory, and antimicrobial effects. In this study, essential oil was extracted from the stem of C. cassia using hydrodistillation via a Clevenger apparatus. The resulting oil, predominantly composed of cinnamaldehyde (92%), was characterized using a multidisciplinary set of techniques, including Nuclear Magnetic Resonance (NMR), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD). NMR, in both time-domain and solution modes, was highlighted as a powerful analytical tool for evaluating chemical composition, molecular structure, and purity. The integration of these techniques provided detailed insights into both the liquid extract and the residual solid material, revealing structural and molecular reorganization after oil extraction. The findings reinforce the potential application of cinnamon oil in food, pharmaceutical, and dental products, especially due to its high cinnamaldehyde content and purity.