A review with 38 refs. With the introduction of the Fourier-Transform technique in the mid-seventies, IR spectroscopy has become one of the most important tools for the characterization of the chem. and phys. nature of polymers. Apart from the increasing availability of a broad range of special sampling devices and detection techniques (attenuated total reflection, photoacoustic and micro-spectroscopy) in the course of the following years, the development of the step-scan technique and the extension from the mid- to the near-IR (NIR) region have had the most significant impact on the applicability of IR-spectroscopy for time-resolved polymer anal. and process control. In the following contribution the principles and exptl. details of the new techniques will be discussed and selected applications from various fields of polymer research shall demonstrate their potential.