Glass and Amberlite particles ranging in size from 0.18 to 1.0 mm were fluidized by supercritical CO2. For a given material in a narrow size range, the volume of the random packing increases exponentially with CO2 mass flow rate. In the supercritical region investigated (35-55 degrees C, 83-124 bar), the bed expansion has relatively weak temperature and pressure dependences due to the counteracting effects of the density and viscosity variations of supercritical CO2. Consistent with conventional particle fluidization correlations, the minimum fluidization velocity (u(mf)) values obtained experimentally depend only on the packing material, size, and fluidization conditions (pressure and temperature). A plot (log u vs log epsilon) of the Richardson-Zaki correlation is nearly linear with the value of the exponent (similar to 2.6) being in the range of values reported for spherical particles. The u(mf) values and terminal velocity (u(t)) predicted with conventional correlations bracket those obtained from experiments, confirming that such correlations may be used for designing CO2-based fluidization processes.