Through comparisons of the photosensitized dimerization of various conjugated dienes, we could identify how different electronic and structural factors affect their reactivities. Being the most reactive, the photodimerization of 1,3-cyclohexadiene is favored both by its long T1 lifetime and its more reactive triplet with a 1,4-diradical character. Thus, pathways to photobiological production of 1,3-cyclohexadiene should be sought, although a drawback is its nonvolatility (b.p. = 80 °C) making it unusable in our previously reported two-step photobiological-photochemical approach to jet fuel hydrocarbons.