Investigations were focused on the kinetics and thermodynamics of nylon 6 fiber dyeing with the hydrogen peroxide-glyoxal redox system. We tried to understand thoroughly the difference between the new redox and the conventional dyeing system, since the mechanism of redox dyeing is a combination of free radical and ionic dyeing, whereas the conventional system is only ionic. The study consisted of measuring the dyeing transition temperature (T D ), diffusion coefficient (D T ), activation energies of diffusion, dyeing affinity, and the dyeing enthalpy and entropy. From the experimental results, the dyeing transition temperature (T D ) in the redox system is lower than that in the conventional system. But the diffusion coefficient (D T ) in the redox dyeing is larger than that in the conventional dyeing. The dyeing affinity of the free radical dyeing type (redox) is lower than that of the ionic type (conventional). Moreover, from the analysis of thermodynamics of dyeing, the enthalpy is found to be positive (endothermal reaction) in the redox system, but it is negative (exothermal reaction) in the conventional one. The entropy is also found to behave similarly, i.e. positive in the redox system, but negative in the conventional dyeing. Finally, the dyeing saturation value in the redox dyeing system is found to be higher than that in conventional dyeing.