Abstract: The invention relates to a method for preparing a colloidal nanoparticle solution, including: (a) dissolving a titanium-oxide precursor, referred to as a precursor, in one or more solvents, referred to as precursor solvents; and (b) chemically converting, preferably by means of hydrolysis, said titanium-oxide precursor and said precursor solvent into a colloidal-solution solvent so as to form titanium-oxide nanoparticles that are dispersed in the colloidal-solution solvent, said colloidal solution having a dynamic viscosity of between 4 and 54 cP at 20° C. and 101,325 Pa. The invention also relates to a colloidal titanium-oxide nanoparticle solution containing a dispersion of titanium-oxide nanoparticles in a solvent or system of solvents, the viscosity of which is between 4 and 54 cP, said solution being particularly obtainable according to the method of the invention, as well as to the uses thereof, in particular for preparing photovoltaic cells.