This work is a review of already existing knowledge about heterocyclic compounds, primary including pyridine and it's derivatives, quaternary ammonium salts and quaternization reactions. Due to their diverse properties, simple preparation and multiple applications, quaternary ammonium salts are the subject of research by many scientists for many years. Quaternary ammonium compounds, including pyridinium salts, have shown a wide variety of interesting biological activities, among others they act as reactivators of human erythrocyte acetylcholinesterase and butyrylcholinesterase inhibited by nerve agents and pesticides. An overview of a few synthesis of quaternary salts of pyridine derivatives introduce the experimental part of this paper, in which three quaternization reactions of pyridine derivatives (nicotinamide and pyridoxal oxime) with 2-bromo-4'-fluoroacetophenone and 2-bromo-4'-methoxyacetophenone were carried out.