Hydrothermally stable alummosilicate MCM-41 analogue with extensive embedded voids was prepared via the controlled coassembly of protozeolitic nanoclusters and soluble silicates in alkaline media. XRD, N-2 sorption results showed that the sample had highly ordered hexagonal mesostructures typical of MCM-41, but the hydrothermal stability was largely improved compared to normal MCM-41 merely from sodium silicates and sodium aluminates. Furthermore, the MCM-41 analogue exhibited tubular morphology in typical SEM micrograph, and embedded voids were extensively distributed in the tubule walls based on TEM observation and N-2 sorption analysis. As a result, the unidimensional nanochannels were interconnected into three-dimensional networks by these embedded voids. NMR results indicated that the MCM-41 analogue had higher cross-linking degree compared to normal MCM-41, which led to the greatly improved hydrothermal stability. This MCM-41 analogue with good hydrothermal stability and increased interchannel accessibility is a potential candidate as catalysts and catalyst supports. (C) 2004 Elsevier B.V. All rights reserved.