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A novel non-hydrolytic sol-gel synthesis of hybrid organosilicates is reported allowing control of micro/mesoporous character of the xerogels by variation of the silicon precursor. The polycondensation reaction of silicon(IV) acetate, Si(OAc) 4 , with 1,3,5-trihydroxybenzene (THB) in dry dioxane at 100 °C produces acetic acid and highly porous amorphous aromatic organosilicate xerogels. Their apparent BET surface areas are as high as 990 m 2 g −1 and the total pore volume is 0.843 cm 3 g −1 . These materials are mostly microporous with a low abundance of mesopores and an average pore size of 3.5 nm. The reaction of HSi(OAc) 3 with THB produced a novel mesoporous material with properties superior to xerogels obtained from Si(OAc) 4 . The BET surface area of 933 m 2 g −1 is retained upon heating and average pore size reached 6.0 nm. The total pore volume of 1.36 cm 3 g −1 is the highest value achieved in porous aromatic organosilicates so far and is comparable to values typical for 3D covalent organic networks (COFs). The materials are stable up to 400–500 °C but they are sensitive to hydrolysis in moist air. The reactions of other silicon precursors (MeSi(OAc) 3 and t BuSi(OAc) 3 ) and larger polyphenol connectors, 1,3,5-tris(4′-hydroxyphenyl)benzene (THPB), 2,4,6-tris(4′-hydroxyphenyl)-1,3,5-triazine (THPTA), and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP), produced materials with less satisfactory properties. [ABSTRACT FROM AUTHOR]