The fluorescence spectrum with a peak around 620 nm and lifetime of 41 +/- 2 ps for 1,3,5-trimethoxybenzene radical cation (TMB.+) in the excited state (TMB.+*) were directly measured with ns-ps two-color two-laser flash photolysis at room temperature. The fluorescence of TMB.+* is assigned to the D-2 -> D-0 transition, showing that TMB.+ is one example of radical cations which violate Kasha's rule. The fluorescence quantum yield of TMB.+* was determined to be 5.4 x 10(-3), and the radiative and nonradiative decay rate constants were 1.3 x 10(8) and 2.4 x 10(10) s(-1), respectively. (c) 2006 Elsevier B.V. All rights reserved.