The rate of the bromine-exchange reaction between gallium bromide and n-propyl bromide in 1,2,4-trichlorobenzene and in nitrobenzene was measured at 19, 25 and $40^{circ}C$, using n-propyl bromide labelled with Br-82. The results indicated that the exchange reaction was second order with respect to gallium bromide and first order with respect to n-propyl bromide. The third-order rate constant determined at $19^{circ}C$ is $2.9{ imes} 10^{-2}l^2{cdot}mole^{-2}{cdot}sec^{-1}$ in 1,2,4-trichlorobenzene and $4.5{ imes}10^{-3}l^2{cdot}mole^{-2}{cdot}sec^{-1}$. in nitrobenzene. The activation energy, the enthalpy of activation and the entropy of activation for the exchange reaction were also determined. Reaction mechanism for the bromine exchange of n-propyl bromide seemed to be similar to those observed in earlier studies with other alkyl bromides.