The tortuosity-porosity relation and internal structure diameters in a selected organogel are studied. The diffusion coefficient measured by pulsed field gradient NMR at short and long observation times can be used to estimate the tortuosity and the pore surface-to-volume (S/V-pore) ratio of a porous material (Latour et al. in J Magn Res A 112: 83-91, 1995; Mair et al. in Magn Res Imaging 19: 345-351, 2001; Mitra et al. in Phys Rev B 47(14): 8565-8574, 1993; Valiullin and Skirda in J Chem Phys 114: 452-458, 2001). The value of S/V-pore allows to calculate the average pore and barrier diameters. In the experiment, the time-dependent diffusion coefficient of toluene in a low molecular weight gelator methyl-4,6-O-(p-nitrobenzylidene)-alpha-D-glucopyranoside (Gluco-NO2) matrix was measured. The results revealed the relation between the diffusion coefficient of toluene and the concentration of gelator Gluco-NO2 in the system. With increasing Gluco-NO2 compound in the sample, the diffusion coefficient of toluene decreases. On the basis of the diffusion coefficient behaviour as a function of time and gelator concentration, the fibrous structure of the gel matrix was identified and the structural parameters of the system were investigated.