Gravimetric sorption experiments were conducted to measure the diffusivity and solubility of toluene and ethylbenzene in a styrene copolymer over a wide concentration and temperature range. Even though the styrene content varied considerately, the solubility of the investigated solvents in different samples of the copolymer were similar. Diffusivity correlations applying the Vrentas-Duda free-volume theory fit the experimental data well. The diffusivity decreases with increasing styrene content. The presence of crystals in the low styrene samples at low temperature did not influence the solubility and diffusivity characteristic.