Temperature wave analysis (TWA) is an originally developed new thermal analysis that makes it possible to obtain the frequency dependent thermal diffusivity as a function of temperature. The thermal diffusivity of every materials, except for electrical conductors, can be obtained for both solid and liquid states in the frequency range from 10 Hz to 2 kHz. The technique enables studies of frequency dependent thermal diffusivity at glass transition, melting and crystallization of polymers. The experimental results for several polymers are reported in the temperature range from room temperature to above the melting point under a constant heating or cooling process.