Steady-state fluorescence measurements have been used to measure the rate of transport of a fluorescent probe (pyrene) out of ca. 250 nm thick films of polystyrene in contact with CO2(sc) at pressures in the range 35-110 bar (estimated CO2 content in the film up to 0.11 weight fraction) and several temperatures (35, 40, 50, and 60degreesC). At constant temperature, the estimated pyrene diffusion coefficient increases by approximately 4 orders of magnitude from the lowest to the highest CO2 content (e.g., from ca. 10(-14) cm(2)/s for ca. 0.04 CO2 weight fraction to ca. 10(-10) cm(2)/s for ca. 0.11 CO2 weight fraction at 60degreesC). We estimate the glass transition pressure at a given temperature (P,(T)) in two ways: (1) from the inflection point of the log D VS MOD Plot, (2) matching log D at a given temperature and P(CO2) to the value obtained for an unswollen film at T-g (D is measured by the rate of loss of the probe into a vacuum).