Cross-linked protein crystals (CLPCs) constitute a novel type of molecular sieves with high porosity. In order to characterize the fully hydrated CLPC, the method of macromolecular porosimetry was applied. This technique allows one to estimate the apparent pore sizes and pore size distribution in solid and soft hydrated porous sorbents directly from size exclusion chromatography. According to this method, CLPCs offer a wide range of pore size (15-100 Angstrom), porosity (0.5-0.8), and pore surface area (800-2000 m(2)/g). These CLPC materials can be made chemically and mechanically stable, and are capable of separating molecules by size, chemical structure, and chirality.