Introduction Polymer characterization has the potential to be particularly useful in assisting the design of sophisticated polymeric materials with dedicated functions. Matrixassisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is an important tool in this technique [1, 2]. Currently, conventional TOFMS instruments used for polymer characterization apply a single reflector with a flight path of approximately 17 m (2.1 m×8 turns) along the spiral ion trajectory, which yields a high mass-resolving power of 80,000 at full width at half maximum (FWHM) for m/z ca. 2500 of a peptide sample. In a previous study, we applied MALDI spiral- TOFMS to the detailed structural characterization of polyphenols [5, 6] and radical-polymerized copolymers . In these former studies [5, 6], we were able to identify the structures of repeating units of polyphenols. In the latter study , copolymer compositions and several types of end-group combinations could be identified, allowing the compositional distribution to be evaluated. In both cases, MALDI spiral-TOFMS could be used to provide an accurate judgment of the mass differences at ca. 16 Da to discriminate O and CH 4 , between which the mass difference is only 0.036 Da. We therefore anticipate MALDI spiral-TOFMS to make a significant contribution to the development of the structural characterization of polymers.