The aim of this study was to investigate the experimental extraction of L-Carnitine (LCAR) from oyster mushroom with supercritical carbon dioxide and methanol as co-solvent. The four variables affecting this process were temperature (40 to 80 degrees C), pressure (10 to 30 MPa), carbon dioxide flow rate (0.5 to 2.5 ml/min) and dynamic extraction time (40 to 120 min). The highest extraction yield was 55.28% (weight basis) which was obtained at 40 degrees C, 19.50 MPa, 2.14 ml/min, and 120 min. Also, the extraction process was modeled using a differential mass balance model in which the comparison between two thermodynamic and genetic methods was used for evaluation the physical significance of the model. The determination coefficient calculated using the genetic method was 95.83%. This clearly indicates the accuracy of the model.