Capsular polysaccharides (CPSs) from the bacterial cell surface are important virulence factors and play an essential role for bacterial survival. CPSs are also important antigens capable of inducing a specific immune response rending these structurally unique glycans attractive targets for antibacterial vaccines development. The first part of the dissertation describes the construction of a collection of 15 novel synthetic oligosaccharides resembling the capsular polysaccharides of Streptococcus suis serotype 9. Differently protected monosaccharide building blocks were synthesized and employed into glycosylations to assemble the oligosaccharides. The second part of the dissertation focused on a multi-drug resistant bacterium Acinetobacter baumannii. The synthesis of repeating unit of CPS from A. baumannii AB5075 as well as two analogues is described. The synthetic oligosaccharides bearing an amine linker are ready for glycan microarray study, identification of the minimal epitope and conjugation.