Spontaneous oscillations in the cathode potential are observed in the alkaline Cu(II)/tartrate and lactate systems when applying current to the electrochemical cell. In the Cu(II)/tartrate system the oscillations induce formation of composite films of Cu and Cu2O on the cathode with a grain size ranging from about 5 to 15 nm. The oscillation period is a function of pH and deposition temperature, A mechanism for the oscillating Cu(II)/tartrate and lactate systems is proposed based on pH changes close to the electrode surface during the deposition process.