The interest of current thesis is a theoretical study of the single electron effects in strongly interacting mesoscopic systems based on quantum Hall effect, where one dimensional edge states play an important role. The bosonization technique is used to take into account a strong electron-electron interaction in such systems. Namely, we theoretically consider the relaxation of an electron wave packet at the quantum Hall edge at filling factor two, the decay of Coulomb blockade oscillations in single electron transistor based on integer quantum Hall effect, and the last question is devoted to the dephasing in electronic Mach-Zehnder interferometer with filling factor one by a strongly coupled Ohmic contact. This investigation is partially triggered by the recent experiments.