The effect of a series of polar, amphiphilic, and nonpolar solvents of various molecular weights on the glass transition (T-g) of polyamide 6,6 (PA66) amorphous phase was studied. The sorption at equilibrium was measured by immersing the polymer in each solvent. Differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS) were used to characterize the T-g of solvent-saturated samples. It was observed that the solvent sorption provokes a drop on the polymer T-g, depending on the interactions between the polymer and the solvents. Polar molecules are absorbed in large amounts and decrease the T-g by more than 80 degrees C, whereas non-polar molecules are absorbed in very small quantities but have a large effect on T-g as well. The sorption equilibrium and T-g shift in the presence of the E10 mixture (10%(vol) ethanol, 45%(vol) toluene, and 45%(vol) isooctane) were also analyzed. A large E10 intake and a T-g drop close to that with pure ethanol are observed. POLYM. ENG. SCI., 51: 2129-2135, 2011. (C) 2011 Society of Plastics Engineers