An investigation was conducted to determine the basic physical characteristics of stainless steel membrane material considered for an aqueous waste separation process and concurrently to develop a procedure for future use in characterizing membrane material. The initial choice of sintered 316L stainless steel material was the result of the need for a robust and acid resistant membrane having the potential for aqueous separations capabilities. The membrane material tested had a nominal filtration rating (particle cut-off) of 0.5 mum and a thickness of approximately 0.123 cm. Characterization tests conducted were used to determine the pore size distribution, mean pore diameter, porosity, and tortuosity of the stainless steel membrane material. Results indicated that the average pore diameter was approximately 2.2 mum and the average of the porosity was determined to be 24.9%. The diffusion tortuosity, determined from the measurement of C-14-labeled sucrose diffusion through the stainless steel membrane, was estimated to be approximately 1.3.