This paper emphasizes on the mechanical characterization of heteropolysiloxane (HPS) derived materials using rheology and acoustic microscopy methods. Dynamic rheological measurements have been performed at the sol and the gel stages with two different precursors. An organic gel-like behaviour has been brought into evidence related to the fact that several microns thick coated layers can be obtained with these materials. On the contrary acoustic analysis revealed a glass-like behaviour for the cured layers. These results confirm the interest of organic/inorganic polymers to design new materials with tailored properties.