Effect of water content in the film-forming solutions on the structure and properties of porous methyl-modified silicate films prepared by acid co-hydrolysis of TEOS and MTEOS with the use of nonionic Brij® 30 surfactant is studied. It is shown by FTIR analysis that hydrolysis of silicon alkoxides is incomplete when 1–2 moles of H2O/alkoxides are used, that leads to a branched and low crosslinked polymer structure characterized by high shrinkage and specific ink-bottle pores. In addition, these films are characterized by lower porosity and higher dielectric constant values in comparison to ones obtained from the sols with 4–8 moles of H2O/alkoxides due to change of interaction between silicate species and surfactant micelles. Effect of water deficiency is the most pronounced if hydrolysis takes place in initially diluted solution compared to the solution prepared by dilution of prior concentrated and aged sol.