Solvents are integral part of the world and so many charge transfer processes take place in a solutions. Unfortunately, not much is known about the microstructure of solvents and solvent mixtures. It is usually assumed that when a mixture seems homogeneous in macro world the same applies for microstructure and reaction environment. Some binary solvent systems have been studied by small-angle neutron scattering (SANS) methods and it has been shown that microheterogenity can occur in some multicomponent solvent systems. Observed heterogeneous clusters show that the solvent molecules are not evenly distributed and the microenvironment around a single molecule can be different from what is usually assumed. Only a few tertiary systems have been studied and our research focuses on the structure of tertiary system consisting of 1,4-dioxane, naphthalene and water.