Two-photon excitation of photobases is used to induce pH changes and control the condensation step of the sol-gel process at the focal point of a laser beam in a confocal configuration. This two-photon microfabrication process, which is usually used in the polymerization of organic monomers, enables the generation of 2D and 3D inorganic Si-O-Si networks of silica based materials with micron resolution.Different variables for the formulation are studied, including the mechanism of condensation, the type of photo initiator, the solvent and the concentration used, as well as the laser parameters.