In the last decades, information regarding the chemistry of the icy moons (those in the outer reaches of the solar system) has been collected and our understanding furthered due to modern telescopes and the success of space missions such as Voyager, Galileo, and Cassini-Huygens. In the present day, there is available data regarding their atmospheric and surface composition. Coupled with gravitational and magnetic data, the geologic structure of these objects may be derived. Cassini analyzed the materials expelled by the plumes of Enceladus granting us the first direct data of the interior composition of an icy moon. Huygens landed on Titan and showed the methane-based hydrologic system on its surface. By comparison, the chemistry of all systems on planet Earth is connected in cycles, including biogeochemical processes. Some work has been done on connecting the atmospheric, surface and interior chemistry of the icy moons to predict which geochemistry processes could be responsible for the origin of organic molecules tentatively detected to date. In this review, we describe what is known or hypothesized about the geochemistry of the Jovian, Saturnian, and Neptunian icy moons, with special emphasis on the subgroup in which liquid water is thought to be a significant part of their internal structure. Prospective hydrothermal activity may explain the presence of key molecules such as CH4 and NH3 and drive cryovolcanic events, especially on icy satellites with rock/water interactions between the silicate core and the subsurface ocean. Such as it happens on Earth, geochemical reactions are essential to originate and maintain life as we know it. Future missions to the icy moons, such as JUICE from ESA and NASA's Europa Clipper, will be searching for habitability signatures on these moons and will be focused on solving their geochemical mysteries. EDITORIAL TRACKING SYSTEM is utilized for manuscript submission, review, editorial processing and tracking which can be securely accessed by the authors, reviewers and editors for monitoring and tracking the article processing. Manuscripts can be upload online at Editorial Tracking System (https://www.longdom.org/submissions/geology-geosciences.html) or forwarded to the Editorial Office at geology@journalsci.org Media Contact: Rooba Journal Manager Geology and Geophysics Email: geology@journalsci.org