Flow injection kinetics was used to investigate the activation energy and thermodynamics parameters of periodate degradation of 2,4-dimethylaniline by catalyzing the reaction with Mn(II) in a mixed medium. The impact of pH and dielectric constant was also investigated. Flow injection kinetics, activation energy, and several thermodynamic parameters have also been recorded. The value of activation energy (ΔE#) for the degradation of 2,4-dimethylaniline is 4.5350 ± 0.1302 kJmol−1, which is consistent with the speculative first-order. The value of other thermodynamic parameters were reported as Arrhenius frequency factor (A) = 3.7660 × 106 ± 0.00372 dm3mol−1s−1; Activation Entropy (ΔS#) = −208.170 ± 0.1498 Jmol−1K−1, Activation free energy (ΔG#) = 66.59 ± 1.163 kJmol−1 and activation Enthalpy (ΔH#) = 1.954 ± 0.0465 kJmol−1.