Hydrophobic Poly(vinylidene fluoride) (PVDF) ultrafiltradon (UF) membranes were successfully wetted in m-phenylenediamine (MPD) solution by applying wetting pressure higher than penetration pressure as calculated by Jurin's law. Afterwards, up to 74.26% of 5000 ppm NaCl solution was removed from polyamide (PA)/PVDF membranes prepared by reaction with trimesoyl chloride (TMC). It was also found that salt rejection ratio was optimized depending on whether the operating pressure was higher or lower than the wetting pressure needed for wetting of MPD solution.