The aim of this thesis is the analysis and study of fragmentation of the polyether polyols using the soft-ionization technique, the type of ionization employed was MALDI, the fragmentation was mainly achieved using Tandem mass spectrometry (MS/MS) and TOF/TOF instrument of the compounds. I determined that high intensity can be obtained using lithium ions as cationizing agent. I identified the series and the chemical compositions of the polymers.