The catalytic oxidation of pyridine carboxylic acids such as nicotinic acid, picolinic acid and quniolinic acid to the corresponding N-oxides has been studied using hydrogen peroxide as an oxidant and Preyssler's catalyst as pure acid, H-14[NaP5W30O110] and mixed addenda, H-14[NaP5W29M0O110]. The highly selective oxidations, gave good yields of the related N-oxides along with decarboxylation of the amines. In the production of pyridine N-oxides, the position of COOH group is found to play an important role in the product type and decarboxylation is only taken place at 2-position of nitrogen. The oxidation reactions were extended to other tertiary amines. (c) 2006 Elsevier B.V. All rights reserved.