This article reports the achievements of the micro-scale (secretory-structure-scale) mathematical modelling of essential oil isolation by supercritical carbon dioxide. Some new experimental and modelling results are presented. The improved model for the supercritical fluid extraction from the glandular trichomes (peltate glands) is introduced. According to the behavior of plant secretory structures during the extraction as well as according to the modelling results, plant material was classified according to the dominant resistance to mass transfer during the extraction process. External mass transfer was the rate limiting step in the extraction from plants with secretory ducts and secretory cavities of citrus family. In the case of extraction from secretory cells, internal diffusion was the rate limiting step. In the extraction from glandular trichomes, external mass transfer, as well as diffusion through the gland membrane influenced the process. (C) 2008 Elsevier B.V. All rights reserved.