An interesting class of materials is mesoporous organosilica materials containing a bridging, organic group along the pore-surface. Such materials are prepared from silsesquioxane precursors of the type (R'O)(3)Si-R-Si(OR')(3) where R is the bridging organic group of interest, in combination with a lyotropic phase as a template for the generation of the pores. A new silsesquioxane precursor, 1,3-bis-(trialkoxysilyl)-5-bromobenzene, and the related mesoporous organosilica material containing bromobenzene groups located at the pore walls are presented in the current publication. The latter precursor allows access to the derivatization reactions known for halogenated aromatic compounds. Materials containing phenyl derivatives can be obtained either by chemical modifications starting from the mentioned precursor on the molecular scale, or the modifications can be performed directly at the surfaces of the porous material. Materials with surfaces containing benzoic acid, styrene, and phenylphosphonic acid are described.