All siloxane-type siloxane-polyhedral oligomeric silsesquioxane [(HSiO 3/2 ) 8 , T 8 H ] copolymers were synthesized by the dehydrogenative condensation of T 8 H with diphenylsilanediol, tetraphenyldisiloxane-1,3-diol or silanol-terminated polydimethylsiloxanes in the presence of diethylhydroxylamine followed by trimethylsilylation. Coating films were prepared by spin-coating of the coating solutions prepared from the dehydrogenative condensation products. The hardness of the coating films was evaluated by a pencil hardness test and was found to increase up to 6H with increases in the curing temperature. Silica gels were prepared by concentrating the coating solution following by pyrolysis. These silica gels showed a specific surface area 449 m 2 /g at 650• C corresponding to the formation of a silica network in response to combustion of the phenyl groups.