The analysis of a technical poly(ethylene oxide) with respect to chemical structure and degree of polymerization has been performed by on-line HPLC/H-1-NMR analysis. Liquid chromatography separates the poly(ethylene oxide) according to the functional end groups. The functionality fractions are directly introduced into a 500 MHz H-1-NMR spectrometer and analyzed with respect to the configuration of the end groups and the molar mass of the polymer chain. The experiments have been conducted under conditions which are common for HPLC separations, i.e. a sufficiently high flow rate, moderate sample concentration, and on-flow detection.