It has been nearly a third of a century since Strobel’s (1973) pioneering study of hydrocarbon chemistry and Axel's (1972) seminal work on the hydrocarbon aerosols. Methane, the parent molecule of hydrocarbons, is abundant on Titan. Photolysis of methane results in the synthesis of more complex hydrocarbons. The hydrocarbon chemistry is unique and rich and the same reactions apply to all reducing atmospheres. The hydrocarbon chemistry inevitably leads to the formation of high molecular weight products, giving rise to aerosols when the ambient atmosphere is cool enough for them to condense. We will review the progress in the hydrocarbon chemistry since the Voyager and Cassini missions (Yung et al., 1984; Li et al. 2014). A number of pathways to organic synthesis from simple to complex hydrocarbons have been identified. Neutral schemes involve radicals such as C3H3 and C3H5. Both ringed and chained compounds can be synthesized. The organic chemistry is a very sensitive function of the H and H2 concentrations in the atmosphere. In fact, we can constrain the concentration of H atoms in the atmosphere from the allene to methylacetylene ratio. One of the spectacular discoveries of Cassini was the prolific activity and presence of a plume on Saturn's tiny moon Enceladus, which offers us a unique opportunity to sample the interior composition of an icy satellite, and to look for interesting chemistry and possible signs of life. Based on studies of the potential habitability of Jupiter's moon Europa, icy satellite oceans can be habitable if they are chemically mixed with the overlying ice shell on million-year time scales. We hypothesize that Enceladus’ plume, tectonic processes, and possible liquid water ocean may create a complete and sustainable geochemical cycle that may allow it to support life. We discuss evidence for surface/ocean material exchange on Enceladus based on the amounts of silicate dust material present in the Enceladus’ plume particles.