Aqueous bromine atoms were produced by laser flash photolysis of 1,2-dibromoethane at 248 nm. in solutions containing bromide ions. Forward and reverse rate constants of the title reaction were determined as functions of temperature. An analysis of potential sources of systematic errors shows that the measured forward and reverse rate constants have relative uncertainties (+/-sigma(k)/k) of similar to10 and similar to25%, respectively, over the temperature range from 10.5 to 50 degreesC. The Arrhenius parameters are (k(f) +/- 10%) = 5.1 x 10(12) exp (-1812/T) M-1 s(-1) and (k(r) +/- 25%) = 2.5 x 10(10)exp (-4068/T) s(-1). The equilibrium constant is found from the ratio of k(f)/k(r): (K-eq +/- 30%) = 2.0 x 10(2) exp (2256/7) M-1 or (3.9 x 1.2) x 10(5) M-1 at 298 K. The reaction entropy and enthalpy are DeltaS(R)degrees = 44 +/- 6 J mol(-1) K-1 and DeltaH(R)degrees -19 +/- 2 kJ mol(-1), respectively. The corresponding reaction reduction potential is DeltaEdegrees = 0.33 +/- 0.01 V, in very good agreement with that calculated from half-cell potentials. In addition, preliminary rate constants for Br-2(-.) + Br-2(-.) --> Br-3(-) + Br- and the hydrogen abstraction reaction (Br-. + BrCH2CH2Br --> (CBrH)-C-.-CH2-Br + H+ + Br-) are reported.