Organic modified siloxanes of the type RSi(OMe2)(2)(CH2)(2)C6D4(CH2)(3)(OMe2)(2)SiR [R = Me (4), R = OMe (5)] were sol-gel processed employing solvents of different polarity (MeOH and THF) to yield the corresponding inorganic-organic hybrid polymers X4a - X5b with different physical properties. These polymers were investigated by multinuclear (H-2, C-13, and Si-29) solid state and H-1 suspension state NMR spectroscopy, including dynamic NMR techniques, in order to correlate the mobilities of these xerogels with physical properties, especially with the cross-linkage.