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Acidic nonionic microemulsions have been used for gelation of tetraethyl orthosilicate (TEOS). It is shown that the release of ethanol will expand the microemulsion region after reaction. The gelation in the nonionic microemulsion (without hydrocarbon) is strongly dependent on surfactant and water. The gelation time strongly increases when surfactant is in excess of 22% by weight. The NMR spectra revealed only a minor reorganization during 4 months of the ethoxy attached to the Si atom for solutions with insufficient amount of water for gelation. This did not change with time (up to 4 months). All-in-all, the reactions with TEOS in acidic microemulsions are similar to those in organic solvents. [ABSTRACT FROM AUTHOR]