This study analyzes the infrared spectrum of the herbicide Clomazone through theoretical calculations and comparison with experimental data. The simulated spectrum was obtained from harmonic calculations with a scaling factor (0.96), reproducing with high fidelity the main vibrational bands observed in the experimental FTIR spectrum (SpectraBase, CAS 81777 89 1). Key coincidences were identified in the regions of aliphatic C–H stretching (2950–2850 cm⁻¹), carbonyl C=O (1715 cm⁻¹), aromatic C=C vibrations (1600–1500 cm⁻¹), C–O and C–N modes (1300–1000 cm⁻¹), and C–Cl signals (700–500 cm⁻¹). Minor differences in band positions are attributed to the limitations of the harmonic model and the absence of solid-phase or solvent effects in the calculation. The overall agreement validates the methodology and demonstrates the usefulness of theoretical calculations as a complementary tool for spectroscopic interpretation and structural characterization of xenobiotics in environmental systems.