Diatoms are intriguing biomineralizing organisms, capable of transporting, processing and metabolizing various forms of “Si”, thus taking part in the Earth's “Si” cycle. They admirably manage the basic (albeit complex) aspects of silica chemistry when they promptly form their cell wall using amorphous silica, starting with monosilicic acid (Si(OH) ₄ ), at mild pH. In spite of extensive studies, the mechanisms for the collection, transport and stabilization of silicic acid from natural waters by diatoms, as well as the formation of their silica cell wall remain elusive. This chapter focuses on various chemical aspects of silicic acid polycondensation, particularly on its stabilization at very high concentrations, prior to biosilicification. The existence of specially designed compartments in the diatom, the so‐called silicon pools has been proposed, without solid experimental proof. While the in vitro silicic acid stabilization at a circumneutral pH can reach up to 120 ppm (~ 2mM), various diatom species can stabilize almost x136 higher concentration (~ 340mM). We attempt to shed light on plausible stabilization mechanisms, by exploring bioinspired chemical approaches involving polyelectrolytes. These interact in various ways with silicic acid, resulting in its stabilization, and thus preventing its polycondensation.