Streptococcus pneumoniae is a Gram-positive bacterium responsible for multiple invasive and non-invasive diseases in humans. According to the World Health Organization this is one of the leading causes of death in children under 5 years. Carbohydrate-protein conjugate vaccines protect infants; since they induce a powerful immune response and generate immunological memory against the capsular polysaccharide of the bacteria. Union between polysaccharide and protein requires sufficient complementary functional groups, which must be introduced without affecting the antigenic, immunogenic and chemical-physical properties of antigen. The present work established a method of Streptococcus pneumoniae capsular polysaccharides serotype 14, 19A and 19F oxidation by oxidation with TEMPO / NaClO / NaBr to generate carboxyl acids in defined primary alcohols of each capsular polysaccharide. The oxidation level was controlled by the initial concentration of NaClO. Undesired fragmentation can be prevented by increasing the molar ratio TEMPO / NaClO. The oxidation site was determined by 1H-NMR and TOCSY. The conjugates to tetanus toxoid were obtained by a carbodiimide or Ugi-4c. The oxidized polysaccharides and the conjugates were characterized by high performance liquid chromatography, colorimetric assay, ELISA, dot blot and 1H-NMR. The conjugates were immunogenic in BALB / c mice and NZW rabbits. Oxidation with TEMPO is a useful method to obtain conjugated carbohydrate-protein vaccines.