Three-dimensional (3-D) porous hydrogels were fabricated by polymerizing 2-hydroxyethyl rnethacrylate around templates of random close-packed poly(methyl methacrylate) microspheres with nominal diameter of 5 or 15 mu m. The templates were leached out to create networks of interconnected spherical pores. Applications,for sphere-templated porous biomaterials include scaffolds for tissue engineering and spatial control of wound healing. This study describes an approach to characterizing pore structure and predicting permeability of sphere-templated porous hydrogels. The materials were embedded in resin, and 1-mu m-plane sections were digitally analyzed with, fluorescence microscopy. The porosity and pore size distribution were determined from. stereological interpretation, and we present novel techniques for obtaining the pore throat size distribution, the number of pore throats per pore, and the tortuosity. A simple apparatus is also introduced for measurement of the hydraulic permeability. Permeability predictions based on quantitative microscopy measurements and on stereology were found to agree closely with permeability measurements. The aptness of the Kozeny equation for spherically pored materials is also investigated. (c) 2005 American Institute of Chemical Engineers