For the first time, kinetics and mechanism of reaction between 4-methyl-benzaldehyde, 4-bromoaniline and methyl acetoacetate is spectrally investigated in the presence of La(NO3)(3).6H(2)O as a catalyst. Based on the experiment data, the overall order of the reaction is two. The second-order rate constant dependency on the temperature was in agreement with the Arrhenius and Eyring equations. The kinetic and thermodynamic parameters of the reaction have been calculated. Furthermore, useful information was obtained from studies of the effect of solvent and concentration of reactants on the reaction rate. The results showed that the second step of the reaction mechanism is a rate-determining step (RDS). The proposed mechanism was also confirmed according to the obtained results and the steady state approximation.