Bioluminescence is a spectacular phenomenon of light emission by some living organisms. It is caused by the oxidation of an organic molecule (luciferin) in the presence of dioxygen, which is catalyzed by the enzyme (luciferase). Light comes from the relaxation of the reaction product: oxyluciferin.[1] Experimenters have synthesized several analogues of oxyluciferin in order to understand the importance of the nature of the light emitter. They have modified the oxyluciferin compound by substituting atom by others (for example the sulfur by a carbon) [2] or adding groups (like allyl group in the benzothiazole ring) [3] on the luciferin compound and measured the bioluminescent emission spectra. We have performed theoretical study on the firefly oxyluciferin, light emitter and its synthesized analogues. [2-3] • Determine the impact of the solvation modeling • Determine the influence of modification in oxyluciferin on the color modulation in the absorption and emission • Simulate the absorption and emission spectra in implicit and explicit water • Compare the theoretical results with the available experimental [2-3] ones.