The enthalpy relaxation and dynamic modulus relaxation processes of amorphous poly(ether imide) (PEI) and two types of crystalline poly(aryl-ether-ether-ketone) (PEEK), low and high crystallinity, were analyzed by the Kohlrausch-Williams-Watts equation. Both crystalline PEEKs and amorphous PEI showed almost the same relationship between enthalpy relaxation time and T-g - T-a in the temperature difference range 10 K < T-g - T-a < 25 K. The enthalpy relaxation time was increased slightly with the increase in degree of crystallinity at a given T-g - T-a. A good correlation was observed between the enthalpy relaxation time and the dynamic modulus relaxation time for both PEI and PEEK, in particular, a linear relationship with slope equal to unity was obtained for PEI.