Process for synthesizing a nanostructured composite material comprising nanoparticles coated in a matrix, characterized in that it comprises the following steps: (a) depositing a matrix for said material in a chamber (3, 3') for synthesizing said material, on a target surface; (b) generating a jet of nanoparticles in a carrier gas with a system (1, 4, 9, 5) comprising an expansion chamber equipped with an outlet orifice separating the expansion chamber from the synthesis chamber (3, 3'); (c) adjusting the distance L between the outlet orifice of the expansion chamber and the target surface and/or adjusting the pressure of the gas present in the synthesis chamber and/or adjusting a factor F ao ∞ V g V p, that takes into account the influence of the mean velocity Vg of the gas present in the synthesis chamber (3,3') and the influence of the mean velocity V p of said nanoparticules in the jet of nanoparticles, in a carrier gas, so that the constant C defined by C = L. N g. M g n. M p. σ. F ao ∞ V g V p has a value less than or equal to two, but not zero, where: N g is the atomic or molecular density of the gas present in the synthesis chamber (3, 3'), M g is the molar mass of this gas, n is the mean number of atoms or molecules per nanoparticle, M p is the molar mass of said atoms or molecules making up the nanoparticles, and σ is the mean geometric effective cross section of said nanoparticles, which are capable of being in an agglomerated or unagglomerated form. (a) depositing a matrix for said material in a chamber (3, 3') for synthesizing said material, on a target surface; (b) generating a jet of nanoparticles in a carrier gas with a system (1, 4, 9, 5) comprising an expansion chamber equipped with an outlet orifice separating the expansion chamber from the synthesis chamber (3, 3'); (c) adjusting the distance L between the outlet orifice of the expansion chamber and the target surface and/or adjusting the pressure of the gas present in the synthesis chamber and/or adjusting a factor F ao ∞ V g V p, that takes into account the influence of the mean velocity Vg of the gas present in the synthesis chamber (3,3') and the influence of the mean velocity V p of said nanoparticules in the jet of nanoparticles, in a carrier gas, so that the constant C defined by C = L. N g. M g n. M p. σ. F ao ∞ V g V p has a value less than or equal to two, but not zero, where: N g is the atomic or molecular density of the gas present in the synthesis chamber (3, 3'), M g is the molar mass of this gas, n is the mean number of atoms or molecules per nanoparticle, M p is the molar mass of said atoms or molecules making up the nanoparticles, and σ is the mean geometric effective cross section of said nanoparticles, which are capable of being in an agglomerated or unagglomerated form. N g is the atomic or molecular density of the gas present in the synthesis chamber (3, 3'), M g is the molar mass of this gas, n is the mean number of atoms or molecules per nanoparticle, M p is the molar mass of said atoms or molecules making up the nanoparticles, and σ is the mean geometric effective cross section of said nanoparticles, which are capable of being in an agglomerated or unagglomerated form.