Electrical properties of sputtered ZrO2 thin films have been studied using impedance spectroscopy, isothermal transient ionic current and current-voltage measurements. ZrO2 have different dielectric properties when fresh, i.e. newly deposited, or aged. A fresh sample can arbitrarily show two different behaviors consisting of a d.c. conductivity with a relaxation peak superimposed on it. The d.c. conductivity shows either of two different values. The aged sample has a lower d.c. conductivity and the relaxation peak is found at much lower frequencies. Fresh samples of ZrO2, also show switching behavior which aged samples never do. Analyses of current-voltage characteristics indicate hopping as the main conduction process.