A spectroscopic study of the initial stage of the Ti(OPri)(4) sol-gel process has been carried out. We have observed that the primary hydrolysis/condensation reaction is complete at low water concentration. At times shorter that the induction time, the reaction results in creation of nanosize nuclei. The most important finding is that the total nuclei mass, which appears almost instantaneously during the stage of mixing, is conserved throughout the process: the particles grow by nucleus agglomeration. The hydrolysis ratio H less than or equal to 1 is sufficient for nucleus creation; H > 1 is needed for particle growth. The initial reagent mixing seems to be the key stage of the process.