Nowadays, pyridinium salts are an important source of raw materials whose applications are found in chemical and industrial industry. By introducing other types of anions or by modifying their structures, their properties can be easily modified. After synthesis of a series of these compounds, a study of their structures has been started. Using Hammett substituent constants, the direct polar conjugation effect on nitrogen group of nucleus were studied. The spectroscopic characteristics determined show that the vibrations of the carbonyl group ν (c=o) are well correlated with the constants of the Hammett substituent as well as the integral intensities B8. Considering the perchlorate ion, the largest integral intensity is found with the perchlorate N- methoxycarbonyloxy-4-methyloxypyridinium with a value of 20,1.10-3 L.mol-1cm-2. The smallest value concerns the perchlorate N- methoxycarbonyloxypyridinium (15, 6.10-3 L.mol-1cm-2). The ν_(c=o) variables vary in the opposite direction and are 1826 cm-1 and 1831 cm-1, respectively. With these two characteristic quantities and the Hammett substituent parameters, the best correlation is found by using σ_R^+. The displacement of the electronic density of the radical on the nitrogen group occurs. Thus, methoxy, phenyloxy and aryloxy carbonyls groups polarize the pyridinium system group and create the conditions for the manifestation of direct polar conjugation effects.