Cocrystallization of all-cis-tetraisopropylcyclotetrasiloxanetetraol and diisopropyl-silanediol gave single crystals, which were proved to have a nano-size tube-like aggregate structure. Six molecules of the cyclic tetraol and four molecules of the diol form an asymmetric unit by means of hydrogen bonding. The structure and properties of the aggregates are discussed in detail, and also the possibility of solid-state synthesis of siloxanes is described.