A new process to obtain volatile oils by fractionation of flower concretes by supercritical fluid extraction was successfully tested for rose and tuberose. Chemical analysis indicated that the quality of the product obtained by means of this technique is superior to that of the corresponding product obtained by the traditional techniques. Microphotographs and extraction results allowed to make some hypotheses on the extraction mechanisms. A model that reproduced the major features of the extraction process of concretes was developed by integration of the solute balance on the concrete and the supercritical solvent. An equilibrium regime in the first part of the process and a variable external mass transfer resistance described the experimental results of the extraction of concretes at different flow rates fairly well.