The rejection of nickel ions on water solutions was studied using aromatic polyamide nanofiltration membrane NF 90 by determination of solution chemistry as the concentration of solution, the pH and ionic strength at 27�C. The experimental results showed that the lower flow solution depends on concentration, solution pH and ionic strength. The solution concentrations showed greater decrease in flux and rejection. Flux decline conducted with a solution of nickel dropped for pH of the solution. At high pH, flux solutions showed higher flux decline than those of low solution pH, while the rejection of ions presented higher rejection. Increased ionic strength had a greater increase in flux decline. The rejection of nickel ions was found to be decreased with decreasing solution pH and increasing ionic strength. Flux and rejection decreased further to the higher ionic strength, which reduces the negative charge repulsion on the surface of the membrane, and thus a decrease of rejection. In addition, comparisons on the decline of flows to co-ions have also been studied in experiments filtration.