Nanoemulsion which exists between marcoemulsion and microemulsion contains droplets with size ranging from 20nm to 200nm. Nanoemulsion is commonly used in cosmetics, foods, agrochemicals, etc due to its ultra-small droplet size and kinetical stablility. Among the techniques for producing nanoemulsion, phase inversion temperature (PIT) method was chosen to produce n-dodecane/brine nanoemulsion in this study because of the advantages of saving energy and surfactant. By PIT method, nanoemulsion can be produced by heating the system close to PIT point followed by a quenching process, because the solubility of polyoxyethylene-type non-ionic surfactant changes with temperature. This study focused on the effect of salt concentration on the production and stability of O/W nanoemulsion since this effect has not been completely understood. The stability of the system was assessed by measuring the particle size and polydispersity index (Pdl) by dynamic light scattering as a function of time and temperature. In the range of salt concentration studied, we found that salt had no significant effect on PIT point and the initial droplets were in similar sizes and size distribution. The system without or with an optimum salt concentration produced the more stable nanoemulsion with lower Ostwald ripening rate compared to others. The most interesting part was the ageing nanoemulsion could be reverted into its initial particle size and Pdl only in the system containing salt. The reversible process could be done by heating the ageing nanoemulsion to a temperature higher than PIT point then cooling to its original storage temperature.