Grass cell walls are major resources for the cellulose-to-ethanol conversion process. However, their enzymatic saccharification is detrimentally affected by lignins and their cross-linking to hemicelluloses. Screening plant cell walls more adapted to the process and monitoring their compositional changes during pretreatment and saccharification steps call for a high-throughput technique of lignins and polysaccharide analysis. Such a performance could be fulfilled by Fourier Transform Infrared (FT-IR) spectroscopy [1, 2]. In this work, FT-IR spectroscopy was assessed as a tool to monitor the compositional changes occurring in the cell walls of the ear-bearing maize internode at three developmental stages. To this end, we first built a FT-IR spectral data base of grass lignins and cell wall polysaccharides. While the FT-IR fingerprint of polysaccharides was in the 1200-800 cm-1 range, the 1800-1450 cm-1 and the 920-790 cm-1 ranges were selected for lignins and hydroxycinnamic acids. This data base was then used to monitor the changes in cell wall composition of ground maize internodes at early (9-leaf stage), medium (female flowering) and late (silage) developmental stages. At early stage, the lignin and p-coumaric acid FT-IR signals could not be detected. At flowering and silage stages, aromatic signals could be observed, including the absorbance band at 833 cm-1 assignable to syringyl units and p-coumaric acid. Finally, FT-IR micro-spectroscopy was applied to map the cell wall polymers in maize internode cross section (flowering stage). In phloem, no lignin signals could be detected while these signals were prominent in the sclerenchyma. The parenchyma cells displayed distinct fingerprints, with lignin signals in the cells far from the bundles and no detectable lignin signals in the cells close to the bundles. In the 1200-800 cm-1 region, the cellulose signals were found to be dominating in the case of sclerenchyma whereas xylan signals were prominent in parenchyma cells.