Depending on the hydrodynamic conditions within the system, the mass transfer can occur by a molecular or convection mechanism. In this work focus has been on the analysis of the molecular diffusion mechanism. The impact of temperature on the value of the diffusion coefficient of sodium chloride solution which diffuses in demineralized water was studied in detail. The values of the diffusion coefficient were determined experimentally using an experimental set up of own design and analytically using the Wilke- Chang equation. The obtained results show that the diffusion coefficient increases with increasing system temperature. An identical trend was obtained by experimental measurements and the application of the above analytical expression. Experimentally and theoretically determined numerical values of the diffusion coefficient do not display an adequate agreement. The reasons for these deviations could be of experimental nature, but also in the choice of an inappropriate analytical expression. The main causes of experimental errors could be temperature variations of the system during the experimental procedure, poor mixing of the solution in the vessel, the appearance of air bubbles in the diffusion cell, inadequate conductometric measurements and possible errors in the preparation of solutions. These experimental errors should be reduced to a minimum in further work, while in the theoretical determination of the diffusion coefficient it is necessary to find an expression that takes into account in more detail the physicochemical properties of the analyzed solutions.