We investigated the kinetics of acetone transport in polycarbonate (PC) under compression and with different thicknesses using the sorption experiment technique. A model combining Case I transport arising from concentration gradient and Case II transport driven by stress relaxation was employed to analyze the transport process. The sorption data are in good agreement with the theoretical prediction. Both the diffusion coefficient D of Case I and the velocity v of Case II transport satisfy the Arrhenius equation. The activation energies of D and v are higher in the stress-free PC than in PC subjected to compression. The activation energies increase with decreasing specimen thickness. The calculated heat of mixing is -5.1 kJ/mol for both the stress-free sample and the sample subjected to compression at 196 MPa, and -8.4 kJ/mol for the sample subjected to compression at 294 MPa. However, the calculated mixing heats are almost the same regardless of specimen thickness. FTIR spectra show no new absorbance peak when the PC is exposed to acetone. The solvent-induced crystallization is confirmed using FTIR spectra. A periodical stripe pattern is observed on the surface when a sample of thickness less than 0.8 mm is exposed to acetone at temperatures greater than 20° C. © 2005 Society of Plastics Engineers.