A spectrophotometric method has been established for the reaction kinetics of phenol oxidative coupling with 4-amino-N, N-dimethylaniline in the presence of potassium dichromate as an oxidant to form C14H14N2O, known as phenol blue. Optimum conditions for the reaction were investigated: maximum wavelength (λ max), linear range, molar absorptivity, and stability constant. The kinetic models were applied to the reaction, indicating that it is a first-order reaction. The activation energy (Ea) and Arrhenius constant (A) were calculated from the Arrhenius equation as 14.89 kJ·mol−1 and 3.75 × 105 s-1 respectively. Thermodynamic parameters were ΔH* 12.37 Kj·mol−1, ΔG* 5.47 kJ·mol−1 and ΔS* 22.77 J·mol−1·K−1 at 30oC.. Results indicate that the formation of the product phenol blue is non-spontaneous and endothermic in nature. Density function theory (DFT) has been done for the comparison between experimental and theoretical results using the common 6-311G(d,p) basis set. The results are in good agreement with each other, proving the reliability of the method. Finally, some preliminary test has been performed to check possibility of the product as dye.