A simple method based on hydrophilic liquid chromatography (HILIC) and electrospray mass spectrometry (ESI-MS) for the detection of monoethanolamine (MEA) degradation products in CO2 post-combustion capture plants has been developed. MEA by-products determination has traditionally been difficult due to analytical separation problems. Even in recent sophisticated methods, this difficulty remains as the major issue often resulting in time-consuming sample preparations. In this work, we have collected samples directly from a real pilot plant and analyzed them, for the first time, by using matrix assisted laser desorption ionization (MALDI)-MS or ESIMS without any separation, both in positive and negative ionization modes. Alternatively, a previous liquid chromatography (LC) run was performed before ESI-MS; traditional reverse phase separation and HILIC were compared. Our results indicated that HILIC separation using an amino modified column, coupled to ESI-MS or ESI-MS/MS measurements, is the suitable method for identifying as many degradation products. Moreover, some plausible degradation mechanisms are proposed to explain some peaks in the spectra. The present work is intended as a preliminary study aiming to show the usefulness of these alternative techniques for this kind of investigations.