A low-energy process for the preparation of a water-in-oil or oil-in-water nanoemulsion wherein the dispersed phase is distributed in the dispersing phase in the form of droplets having a diameter ranging from 1 to 500 nm, comprising: 1) the preparation of a homogeneous water/oil blend characterized by an interface tension lower than 1 mN/m, comprising water in an amount of 30 to 70% by weight, at least two surface-active agents having a different HLB, selected from non-ionic surface-active agents, anionic surface-active agents, polymeric surface-active agents, said surface-active agents being present in a quantity from 5 to 50% by weight of surface-active agents and the weight ratio between the surface-active agents produces a HLB value higher than 8; 2) the formation of said water-in-oil or oil-in-water nanoemulsion by dilution of the blend in a dispersing phase consisting of oil or water with the addition of a surface-active agent, selected from non-ionic surface-active agents, anionic surface-active agents, polymeric surface-active agents, the quantity of the dispersing phase and surface-active agent being such that: - when a water-in-oil nanoemulsion is obtained, said water-in-oil nanoemulsion has a HLB value ranging from 6 to 14, lower than that of the blend and comprises a quantity of water which varies from 1% to 30% by weight, total surface-active agents from 0.1% to 20% by weight, the complement to 100% by weight consisting of oil; - when an oil-in-water nanoemulsion is obtained, said oil-in-water nanoemulsion has a HLB value higher than 10, higher than that of the blend and comprises a quantity of oil which varies from 1% to 30% by weight, total surface-active agents from 0.1% to 20% by weight, the complement to 100% by weight consisting of water. 1) the preparation of a homogeneous water/oil blend characterized by an interface tension lower than 1 mN/m, comprising water in an amount of 30 to 70% by weight, at least two surface-active agents having a different HLB, selected from non-ionic surface-active agents, anionic surface-active agents, polymeric surface-active agents, said surface-active agents being present in a quantity from 5 to 50% by weight of surface-active agents and the weight ratio between the surface-active agents produces a HLB value higher than 8; 2) the formation of said water-in-oil or oil-in-water nanoemulsion by dilution of the blend in a dispersing phase consisting of oil or water with the addition of a surface-active agent, selected from non-ionic surface-active agents, anionic surface-active agents, polymeric surface-active agents, the quantity of the dispersing phase and surface-active agent being such that: - when a water-in-oil nanoemulsion is obtained, said water-in-oil nanoemulsion has a HLB value ranging from 6 to 14, lower than that of the blend and comprises a quantity of water which varies from 1% to 30% by weight, total surface-active agents from 0.1% to 20% by weight, the complement to 100% by weight consisting of oil; - when an oil-in-water nanoemulsion is obtained, said oil-in-water nanoemulsion has a HLB value higher than 10, higher than that of the blend and comprises a quantity of oil which varies from 1% to 30% by weight, total surface-active agents from 0.1% to 20% by weight, the complement to 100% by weight consisting of water. - when a water-in-oil nanoemulsion is obtained, said water-in-oil nanoemulsion has a HLB value ranging from 6 to 14, lower than that of the blend and comprises a quantity of water which varies from 1% to 30% by weight, total surface-active agents from 0.1% to 20% by weight, the complement to 100% by weight consisting of oil; - when an oil-in-water nanoemulsion is obtained, said oil-in-water nanoemulsion has a HLB value higher than 10, higher than that of the blend and comprises a quantity of oil which varies from 1% to 30% by weight, total surface-active agents from 0.1% to 20% by weight, the complement to 100% by weight consisting of water.