A new method is developed for the removal of nitrate ions from water. Nitrate ions can be removed from water almost completely, with a mobile carrier, by counter-transport of chloride ions through a supported liquid membrane. The transport characteristics of this process, in which the water phases are flowing parallel to flat membranes, are described. The results show that depending on the experimental conditions the flux is determined by the diffusion of the carrier through the membrane or by the diffusion of the nitrate ions through a laminar water layer at the feed side. The selectivity of the membrane, which depends on the type of the organic solvent, determines the influence of the chloride concentration in the stripping phase on the membrane flux. Furthermore the effect of carrier concentration is investigated.