In plasma spraying temperature and velocity of the sprayed particles are among the most important parameters influencing the microstructure and properties of the deposited coatings. However, the sprayed particle state is influenced by uncontrollable parameters such as the wear state of the electrodes. In order to investigate the influence of the electrode wear state on sprayed particles, a long-term experiment was conducted during which on-line measurements of plasma sprayed yttria-zirconia powder were performed. Results show that even though input parameters were kept constant during the experiment the state of the sprayed particle changed significantly and coatings prepared at different spraying times have different microstructures and can have different properties. However, by changing some input spray parameters it was possible to retrieve the initial sprayed particle state and coating microstructure.