A corrugated pore structure model (CPSM-nitrogen)(9) was employed to define a novel pore structure tortuosity concept. An empirical correlation is proposed for the prediction of tortuosity factors tau (CPSM) as follows: tau (CPSM) = 1 + A[(D-max,D-eff - D-min,D-eff)/D-mean](N-S - 2)(a). Constants A and a are adjustable parameters. The second factor reflects the influence of the intrinsic pore size distribution, and the third expresses the contribution of the nominal pore length parameter Ns. The latter is, by definition, the number of pore segments forming a single corrugated pore of the CPSM pore configuration model and represents the frequency of pore cross section variation per unit length along a characteristic catalyst pellet dimension. The determination of Ns and (D-max,D-eff - D-min,D-eff)/D-mean is accomplished by fitting the CPSM model over the pertinent nitrogen sorption hysteresis data. Coefficients A and a were found to be A = 0.69 and a = 0.58 by applying the empirical correlation for two specified materials of known tortuosity. The tortuosity factors for an anodic aluminum oxide membrane, MCM-41 materials, dried lignite, a porous glass, and several HDS catalysts were predicted to be 2.60, 1.12-1.13, 1.33-2.79, 6.60, and 2.75-10.07, respectively. Such values approximate the literature data. Mercury porosimetry runs on the HDS catalysts showed a proportional increase in mercury entrapment with an increase in the corresponding tau (CPSM) values. The tortuosity factor of lignite increases proportionally with the pore volume evolution. Further testing of the proposed correlation requires a rigorous analysis of diffusion phenomena, based on the CPSM pore structure configuration, combined with effective diffusivity measurements.