While the direct photosynthetic production of 1,3-dienes by microbes is still in its early stages with too low production rate of dienes for large-scale applications, 21 these compounds can also be produced through biomass processing (Figure ). Plant oil derivatives and microalgal lipids have been used for a range of chemical transformations, including oligomerizations and olefin metathesis. The latter can produce 1,4-cyclohexadiene as a common byproduct, and this compound can be further converted to 1,3-cyclohexadiene via photoisomerization. Besides the biological production of 1,3-cyclohexadiene, other industrially important dienes can be produced via a number of renewable approaches, including (i) catalytic conversion of bio-derived ethanol, C4 alcohols and diols to produce 1,3butadiene, (ii) bio-based production of 2,3-dimethyl-1,3-butadiene by acid-catalyzed dehydration of pinacol in ionic liquids, and (iii) 1,3-pentadiene production from lignocellulose biomass. Although several studies focused on the production of dienes from the fermentation of biomass sugars, none of the pathways have been commercialized for industrial production. Taken together, several (photo)biological approaches are being developed for the production of conjugated dienes. Likewise, several methods for the conversion of small hydrocarbons into fuels exist, spanning from traditional and commercially established C-C bond-forming reactions, e.g., Fisher-Tropsch synthesis and acid-catalyzed oligomerization, to more recently developed thermal and/or metal-catalyzed reactions. From a sustainability perspective, the routes to oligomerize small hydrocarbons need to be further developed in order to reduce the environmental impact. Here, photochemical oligomerization reactions triggered by visible or near-ultraviolet light have significant importance for the development of such routes as these reactions can utilize sunlight as the main energy source. In this context, we recently revealed that mono-and sesquiterpenes with conjugated diene units can be photodimerized with solar light to products that can serve as biodiesel and lubricant oils. Thus, even though small and volatile 1,3-dienes can be especially suitable for biotechnological production using photosynthetic microorganisms, there is also a diversity of renewable sources of small conjugated dienes. Combined with their sunlight-driven photodimerization this can be a route to reduce the environmental impact of jet fuel production (Figure ).