The knowledge of the absorption spectrum of hydrated electron is of importance in numerous pulse radiolysis studies because it is often used for dosimetry or for second-order rate constant determination. We present a direct method for the evaluation of the molar absorption coefficient of the hydrated electron. It is based on the wavelength measurement of isosbestic points during the reaction of e(aq)(-) with the methylviologen MV2+ cations which leads to the formation of MV+center dot. The molar absorption coefficient of hydrated electron is obtained using the value of the molar absorption coefficient of MV+center dot at the isosbestic point at 600 run, i.e., epsilon(600nm),(MV+center dot) = 13500 +/- 300 L mol(-1) cm(-1). Therefore, at the maximum of the absorption spectrum of e(aq)(-) at 715 nm, the value is e(715nm,(eaq-)) = 19700 +/- 400 L mol(-1) cm(-1). The absorption spectrum of the hydrated electron has been re-evaluated and completed from 260 to 850 nm.