And can another small conjugated diene than isoprene provide for a more efficient photodimerization? We utilized 1,1-dinaphthylmethanone as photosensitizer (PS, Figure ) as it has been identified as a suitable photosensitizer under solar irradiation. The effects of solvent viscosity, dilution, and photosensitizer loading on the dimerization yields were also mapped out, and these factors were optimized considering conditions that are relevant for photobiological diene production. Our work can provide insights that will benefit future efforts on the combined photobiological-photochemical production of kerosene-type biofuels.