Fouling is a problem without a satisfactory solution in nanofiltration process. The fouling development causes low performance and reduction of the membrane time life. The aim of this work was to evaluate the behavior of salts significantly present in the sea water in fouling formation on the membrane surface. A commercial nanofiltration membrane (NF-90-400), which was developed for sulphates removal process, was particularly investigated. The permeation experiments with sulphates solution were carried out during seven days; permeate flux and effluent conductivities were monitored. Temperature, transmembrane pressure, concentration, and flow velocity of the feeding solution were kept in 25ºC, 30 bar, 4.000 mg/L, and 0,030 m/s, respectively. The selected membrane showed great efficiency in the sulphate elimination for simple solutions and for binary solutions, it was observed that variation in the ionic force affects the efficiency of sulphates removal. Variations in DP when the solution of work was synthetic sea water affects in a significant way the incrustation characteristics.