The kinetics of thermal degradation and lifetime of poly(aryl ether ketone) containing 2,6-naphthalene moieties (PANEK) in nitrogen and in air were studied with dynamic thermogravimetry. The results showed that the thermal stability of PANEK in air was substantially less than that in nitrogen. The kinetic parameters for PANEK, including the activation energy, the reaction order; and the frequency factor of the degradation reaction, were analyzed with the Ozawa method. The lifetime of PANEK decreased gradually from 1.09 x 10(7) to 0.65 x 10(2) min as the temperature increased from 200 to 400 degrees C in air and from 2.12 x 10(8) to 3.30 x 10(2) min in nitrogen. These lifetime parameters indicated that the service/process temperature had a strong influence on PANEK. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 904-909, 2009