► Characterization of plant cell wall derived oligosaccharides using HILIC–ELSD–MS n . ► Complex mixtures of neutral and acidic oligosaccharides can be separated. ► Oligosaccharides with same net charge but different DP can be separated adequately. Analysis of complex mixtures of plant cell wall derived oligosaccharides is still challenging and multiple analytical techniques are often required for separation and characterization of these mixtures. In this work it is demonstrated that hydrophilic interaction chromatography coupled with evaporative light scattering and mass spectrometry detection (HILIC–ELSD–MS n ) is a valuable tool for identification of a wide range of neutral and acidic cell wall derived oligosaccharides. The separation potential for acidic oligosaccharides observed with HILIC is much better compared to other existing techniques, like capillary electrophoresis, reversed phase and porous-graphitized carbon chromatography. Important structural information, such as presence of methyl esters and acetyl groups, is retained during analysis. Separation of acidic oligosaccharides with equal charge yet with different degrees of polymerization can be obtained. The efficient coupling of HILIC with ELSD and MS n -detection enables characterization and quantification of many different oligosaccharide structures present in complex mixtures. This makes HILIC–ELSD–MS n a versatile and powerful additional technique in plant cell wall analysis.