A new class of bifunctional periodic mesoporous organosilicas (PMOs) composed of organosilicate building blocks with two different silicon sites have been synthesized from the single-source bifunctional organosilica precursors tris(triethoxysilyl-ethyl)ethoxysilane and bis(triethoxysilylethyl)diethoxysilane, respectively denoted MT3-PMO and DT2-PMO. The synthesis of these PMOs is acheived by the co-assembly of a triblock-copolymer Pluronic P123 template with the bifunctional organosilica precursor under acid-catalyzed and inorganic-salt-assisted conditions. After template removal through solvent extraction, the MT3-PMO and DT2-PMO so obtained show well-ordered mesopores and display large pore diameters (6-7 nm) and pore volumes (0.6-0.8 cm(3) g(-1)) with a narrow pore-size distribution and high surface areas (700-800 m(3) g(-1)).