The effect of temperature on the dyeing rate constant h, diffusion coefficient D, time of half-dyeing t(1/2) was evaluated for the dyeing of polyester fibers with two disperse dyes, an azo and an anthraquinone dye. Activation energies of diffusion E were calculated. The polyester dyeing equilibrium was also studied and the partition coefficient K and standard affinity Delta(mu)degrees at various temperatures were determined for the anthraquinone dye. Standard enthalpy DeltaHdegrees and standard entropy DeltaSdegrees of dyeing were also obtained. The same equilibrium parameters were not obtained for the azo dye because of its dyeing behavior. A similar kinetic and equilibrium study was made for the pure azo and anthraquinone compounds free from the dispersing agents present in the commercial dyes and the results are discussed.