The spectroscopic parameters of 4,7-bis(2-thienyl)-1,2,5-oxadiazolo[3,4-c]pyridine (DTOP) were determined which was designed as a red-emitting dye for the electroluminescent (EL) device. The main optical transition of DTOP is attributable to La-1, and therefore, the fluorescence maximum shifted to the red side to reach to 630 nm according to the solvents. Although the non-radiative transition rate was enhanced, when the fluorescence maximum shifts to the longer than 610 nm, DTOP maintains the higher radiation transition probability. (C) 2002 Published by Elsevier Science B.V.