Chalcogenide aerogels (chalcogels) are typically synthesized with thiolysis, aggregration of nanoparticles, and metathesis of chalcometallate. Especially, the metathesis of chalcometallate enabled generalized synthesis of chalcogel with flexible choice of central metal cations and chalcometallate. Although recent developments of chalcogel achieved high surface area and unconventional surface functionality with chalcogenide, chalcogels are amorphous structures with lack of localized structural control, which hinder further tuning of pore structure, crystallinity and surface functionality. We have investigated local structure of thiostannate and thiomolybdate chalcogels. In addition to metathesis reaction, the kinetic control of chalcogel formation enables additional reaction pathways, such as condensation with coordination transformation and crystallization. The precise local structure control of thiomolybdate chalcogel enabled high performance electrocatalyst for hydrogen evolution reaction.[1] Furthermore, the coordination transformation of thiostannate enabled new synthetic route and local structure control of chalcogel.[2] For high performance aqueous radionuclide-adsorption, the well-defined crystalline Na-Mn-Sn-S chalcogel enabled efficient Cs⁺ and Sr²⁺ ion exchange reactions.[3]