The effects of the addition of non-toxic modifiers (ethanol, water, and canola oil) in supercritical carbon dioxide (SC-CO2) extractions from tomato skins were investigated. The extraction efficiency was improved by the addition of any of the three modifiers. Various temperatures (45 degrees C, 60 degrees C, and 75 degrees C) and pressures (25, 30, and 35 MPa) for the modified extraction processes were also compared. The highest yield was achieved at the highest temperature (75 degrees C) and highest pressure (35 MPa). For the three single modifiers, yields increased with increasing amounts (from 5% to 10%) of the modifiers. The highest lycopene yields were obtained with 15% olive oil at 45 degrees C and 10% olive oil at 75 degrees C. For mixtures of binary and ternary modifiers, the mixture of ethanol (10%) and olive oil (10%) achieved the highest extraction efficiency (36.6% at 45 degrees C, and 56.8% at 75 degrees C). It might be caused by the combined synergetic influences of enhanced adsorption on the polar sites of the matrix by ethanol and the increased solubility of lycopene by olive oil. Cluster analysis was applied to build the relationship between the lycopene yields and co-solvent effects. The addition of olive oil also slightly increased the proportion of cis-isomers in the lycopene extract. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.