Kinetics of the essential oil hydrodistillation from sweet flag (Acorus calamus) rhizomes: comparison of basic models essential oil; extraction; hydrodistillation; sweet flag; kinetics; modeling Background: This study investigated the hydrodistillation process for extracting essential oil from sweet flag (Acorus calamus) rhizomes. The primary objectives were to evaluate the influence of the water-to-rhizome ratio on both the yield and chemical composition of the essential oil and to model the extraction kinetics. Results: The water-to-rhizome ratio was found to significantly influence the yield of essential oil, with the highest yield (1.36 ±0.01%) obtained at a ratio of 11:1. However, variations in this ratio did not result in significant changes in the chemical composition of the oil. A first-order kinetic model was identified as the most suitable for describing the hydrodistillation process, offering simplicity and strong agreement with experimental data. Conclusion: The kinetic profile revealed a rapid initial increase in yield, corresponding to the washing phase — where readily accessible oil on the surface is removed—followed by a slower ‘diffusion’ phase, during which the essential oil gradually diffuses from the rhizome matrix into the distillate. © 2025 Society of Chemical Industry (SCI). https://unilib.phaidrabg.rs/o:8230 doi:10.1002/jctb.70076 application/pdf 1021974 bytes info:eu-repo/semantics/article All rights reserved J Chem Technol Biotechnol 2025 startpage: 1 endpage: 10 2025 Mijailović, Miljojka Tadić, Vanja Krstić, Ivan Avramović, Jelena Veličković, Ana Zahitović, Anđela Veljković, Vlada Krstić, Miljana eng