The kinetics of transalkylation and isomerization of o-diethylbenzene (o-DEB) in the presence of benzene (B) using trifluoromethanesulphonic acid as a catalyst has been studied. On the basis of the product distribution obtained, transalkylation, disproportionation, and isomerization reactions have been considered. The main product of the reaction was ethylbenzene. These reactions are conducted in a closed liquid batch reactor with continuous stirring under dry nitrogen and atmospheric pressure over the temperature range of 288-308 K. Power law type model have been tested for the main transalkylation and disproportionation reactions, while the isomerization reactions followed a first-order mechanisms. Increasing the molar ratio of B to o-DEB resulted in decreasing the yield of ethylbenzene. The apparent activation energy of the transalkylation reaction was found to be 50 kJ/mole, while that of disproportionation reaction was 29 kJ/mole. The reproducibility of the experimental product distribution occurred with an average relative error of 5%.