The behavior of titanium and zirconium alkoxides towards K h /K c ratios has shown that in the sol state, silanol Si-OH groups are more stable than the Ti-OH or Zr-OH groups. complexation and water addition is analyzed through water titration and calorimetric experiments. A simple model is Moreover, this study has shown that the proton concentration not only affects the kinetics, but also the final composition presented, which allows evaluation of the mean hydrolysis and condensation constants, K h and K c , of both pure and of the system. Calorimetric studies of the complexation and hydrolysis/condensation reactions have highlighted the role complexed transition metal alkoxides in the sol state, through the analysis of consumed water versus initial hydrolysis ratio of coordination unsaturation of the transition metal alkoxides in the exothermicity of these reactions, clearly demonstrating curves. These constants allow comparison of the extents of the hydrolysis and condensation reactions for sols obtained that coordination unsaturation is the driving force behind the reactivity of these alkoxides towards nucleophilic species from several alkoxide precursors. The complexation ratio only affects the condensation constant K c , whereas the (e.g. water, complexing ligands, polar solvents). hydrolysis constant K h remains unchanged. Analysis of the