The characterization of synthetic polymers and complex oligomeric mixtures by a combination of different mass spectrometry (MS) techniques is the main topic of this dissertation. Ion mobility (IM) separation and/or tandem mass spectrometry (MS2) were interfaced with single stage mass spectrometry for the fast, complete, precise and accurate characterization of different polymers, biopolymers, and biodegradation products. Additionally, the development of a mass spectrometry protocol for the quantitation of proteins adsorbed on different polymer surfaces was accomplished in this dissertation. Over the passed years, synthetic routes for the creation of PEGs have been modified by the elimination of organic catalysts and solvents and the application of green chemistry for the generation of new polymers. In Chapter 4 of this dissertation, MS and MS2 were employed, as the main analytical techniques, for the structural elucidation of enzyme-catalyzed, functionalized PEG and tetraethylene glycol (TEG) biomaterials. The samples analyzed were synthesized by two different processes, transesterification and Michael addition reactions, both of them using CALB as the catalyst. In Chapter 5 of this dissertation, polylactide was degraded using Proteinase K and its biodegradation products were analyzed by MS and MS2. Elucidation of its degradation products is important to the biomedical community; knowledge of these products helps to see any toxicity problems with the use of this polymer. The MS and MS2 results showed that the degradation products are short polylactide chains, down to the monomer. No other, potentially dangerous organics were detected. In the following chapter of this dissertation (Chapter 6), the adsorption of three model proteins onto two different surfaces was evaluated over a pH range. The results were explained on terms of polymer chemistry, surface morphology, proteins' isoelectricpoints and molecular dimensions. Finally, Chapter 7 reports how derivatization, degradation, or chromatographic separation can be avoided for the analysis of complex systems, if multidimensional mass spectrometry methods combining ion mobility separation and different ionization techniques are employed. Using this new approach complex poly([alpha]-peptoid) samples were characterized. The results showed that the main product in the system contained the N-heterocyclic carbene (NHC) moiety that served as ring-opening polymerization catalyst. Furthermore, it was demonstrated that elimination of the NHC segment leads to cyclic poly([alpha]-peptoid)s that have very similar conformations with comparably sized polypeptides.