A new templating method using small, inexpensive nonsurfactant chemicals has been developed facilitating the synthesis of hydrothermally stable foam-like mesopore networks with high surface areas.Porous materials are of fundamental importance in science and technology. 1 Various templates are employed to direct the synthesis of uniform micro-, meso-and macro-pores. Principally, three types of templating have been reported thus far, i.e templating by individual molecules giving rise to micropores, by micelles giving rise to mesopores and by emulsions or latex particles giving rise to macropores. [2][3][4][5] Here, we report a new templating method for well defined mesoporous (siliceous) oxides (denoted as TUD-1, Fig. 1), 6 in which small, non-surfactant templates direct the formation of mesosized structural features during the polycondensation of inorganic species upon temperature increase during synthesis.The key to a successful formation of mesopores is the careful control of the intermolecular interaction among organic templates and inorganic species, i.e. matching the type of template molecule with the temperature regime used. With a system initially composed of three different components, (i.e. water, silica source and template) taking account of the change in the nature of interactions between the different constituents with temperature, we were able to synthesize a new material that is characterized by well-defined pores with an easily tunable mesopore size distribution (25-250 Å in diameter), threedimensional connectivities (foam-type structure), high surface areas (up to ca. 1000 m 2 g 21 ), and high thermal and hydrothermal stability (negligible degradation at 650 °C for 12 h or boiling in water for 2 h, little degradation after heating to 1000 °C for 2 h or boiling in water for 17 h).The starting point of our investigation was the desire to examine whether large pores in structured silicas might be templated, not by micelles or by very large and complex organic molecules, but by aggregates of simpler molecules. Following some preliminary investigations, triethanolamine was selected as a small, inexpensive and stable organic template with a high boiling point (ca. 340 °C) and good miscibility towards water, alkoxysilanes (Si-source) and the silica species generated by their hydrolysis. The new methodology also allows the facile introduction of catalytic sites (acid, base, redox) as well as micropores during the initial synthesis stage.In the first step, a homogeneous mixture is obtained by mixing tetraethylorthosilicate (TEOS), triethanolamine (TEA) and water at room temperature. † After aging and drying in air, this mixture solidified and formed a homogeneous gel, the X-ray powder diffraction pattern of which showed no discernible peak. We interpret these data as deriving from a largely hydrogen-bonded siliceous composite polymer: the initial hydrolysis of TEOS was followed by the partial condensation of the resulting silanol species with each other and with some of the TEA, forming mixtures of mono-and...