The evaluation of phase equilibria and solubility properties through theoretical approaches is a well-known field, where a significant amount of models are able to describe them with a good degree of accuracy. However, the simultaneous calculation of transport properties together with thermodynamic phase properties still remains' a challenge, due to the difficulties in describing the behavior of properties like the viscosity of fluids with the same approach. In this work, the free-volume theory (FVT) has been couple the soft-SAFT equation for the first time to extend the capabilities of the equation to the calculation of transport properties. The theory has been first tested using simulation data of the viscosity of the Lennard-Jones (LJ), fluid and 14 chains at near-zero density values. Several trends of the Viscosity parameters With the length of the chain over a wide range of temperature and pressure. Good agreement has been found at all chain lengthains, except for some deviations prediction and results are compared with experimental data. The been applied parameters where viscosity is a key property, en The three viscosity parameters were fitted to viscosity, data of the pure fluid at several isotherms or isobars, whereas the density and pressure (Or temperature) Were taken from the soft-SAFT output. Again, the effect of these parameters on the viscosity has been investigated and compared with results obtained for the chains and with previous work of other predictive other authors. The new equation performs very we in cases, with a global average absolute deviation of 2.12% an shows predictive for heavier compounds. This empowers soft-SAFT with new capabilities, allowing the equation to calculate phase; interfacial, and transport properties' with the same model an degree of accuracy..