Expanded bed adsorption (EBA) is an integrated technology for capturing target proteins directly from unclarified feedstock. The specially designed adsorbent is essential for the formation of a stable expanded bed. Using the method of water-in-oil suspension thermal regeneration, a novel type of composite porous particles for expanded bed application was prepared with stainless steel powder (SSP) as the densifier and cellulose as the skeleton. The preparation conditions were explored, and two size fractions with different SSP contents were obtained with mean particle sizes of 100 and 170 mu m. The composite particles showed a spherical appearance, suitable size and size distribution, appropriate wet density of 1.2-1.8 g/mL, water content of 50-80%, porosity of 80-90%, pore radius of 30-40 nm, and specific surface area of about 50 m(2)/mL of wet particles, and the stable expanded bed with an expansion factor of 2-3 could be achieved under varying flow rates. In addition, the influences of SSP addition on the physical properties were analyzed, which provided some useful information on the design of EBA adsorbents. A linear relationship between the particle wet density and the SSP/cellulose viscose ratio was found. The addition of SSP into the cellulose skeleton showed little effect on the porosity, specific surface area, and pore radius in the particle, which verified the prepared composite particles are potentially suitable for expanded bed application of biomolecule separation.