TiO2 sol and gel systems have been synthesized by hydrolysis of titanium butoxide in microemulsions W/O. Different systems compositions were prepared at constant W-o = [H2O]/[AOT] and changing R = [H2O]/ETi(BuO)(4)]. Experimental measurements show a progressive increase of the viscosity with time, characteristic of a sol-gel transition. The rheology of the transition was studied by following the behavior of viscoelastic parameters (G', G " and eta*) as a function of time at different frequencies. The possibility to apply standard percolation theory was discussed. The application of two alternative growth models - either 'fractal growth model' or 'nearly linear growth model' - has been analysed.