The intramol. energy transfer of the title compounds, e.g., I and 2-p-tolyl-5-p-biphenylyl-1,3,4-oxadiazole have been studied by steady state fluorescence emission spectra. The efficiency of the intramol. energy transfer is higher than that of the intermol. energy transfer. The efficiency of the singlet-singlet transfer is 100%. The fluorescence lifetime and phosphorescence mean lifetime of the donor, of the acceptor and of the biochromophore compounds have been determine

Key words: BIPHENYL P, CARBOXYLIC ACID ESTER, EXCITED STATE, CHROMOPHOR, REACTION RATE CONSTANT, ENERGY TRANSFER, OXDIAZOLE, TETRAHYDROFURAN P, DIOXANE, FLUORSCENCE DECAY