A new method for corrosion monitoring of metals and alloys is presented. It is based on the change of the radiofrequency (RF) wave propagation in a microstrip line during its corrosion. The microstrip line is produced in the same metal as the mechanical structure under monitoring. The studied frequencies correspond to the ISM bands. During the corrosion process, measured transmission decreases from 0 to 40 dB. This lost is clearly explained by simulations. Consequently, experimental data and simulations results provide fundamental basis on the sensing mechanisms of the method and evidence, in particular, the possibility to distinguish between localized and uniform corrosion. Due to the nature of the method, the sensitive microstrip can be very easily integrated through different architectures into RF wireless sensors. As the consequence, the proposed method should be considered as promising and reliable tool for corrosion monitoring of several materials exposed to various environments.