Poly(dodecyl methacrylate-co-N-isopropylacrylamide) gels were prepared with and without a pore former (PEG) in ethanol at 70 degrees C by free radical cross-linking polymerization method. These gels were used to separate limonene + linalool mixtures with different fractions. The selectivity values were higher than 1 for each gel synthesized with PEG and without PEG. In equilibrium, selectivity values of gels synthesized without PEG in 90/10, 80/20, and 70/30 limonene + linalool binary mixtures were calculated as 1.1, 1.9, and 2.1, respectively. The corresponding gels synthesized using PEG have selectivity values as 1.3, 1.9, and 2.2. Despite slightly effect of pore former on selectivity, it has a relatively significant effect in time regions before arriving equilibrium, giving the idea of selecting optimum time region to separate binary mixtures. Solubility parameter of the gel was predicted by group contribution methods to determine the relationship between selectivity and solubility parameter difference of binary combinations of limonene, linalool and gel. Solubility parameter difference calculated from Hoy method showed that the value of each solubility parameter contribution for gel-linalool binary was the lowest with the values of 0.02, 1.7, and 4.8 for disperse, polar and H-bonding contributions, respectively verifying the selectivity of the gels for linalool. The gel synthesized using PEG shows a swelling value change for temperatures higher than 40 degrees C in the direction of decreasing but the gel synthesized without PEG has approximately constant equilibrium swelling value (ESV). This result indicates that the use of a pore former may be an important parameter in the recovery process of the extracted components after the separation procedure.