An electrochemical method was applied to grow crystals of La 2 CuO 4 and Nd 2 CuO 4 at temperatures below 400°C in a zirconium bath using molten NaOH as an electrolyte. The La 2 CuO 4 crystal grown at 320°C shows superconductivity with the onset transition temperature of 25 K without any heat treatment in oxygen. The results of EPMA, AES and iodometory revealed that the crystal is oxygen rich La 2 CuO 4 + δ , without any substitution of La by Na. The crystals seem to be highly oxidized in the process of the electrochemical deposition. In the case of Nd 2 CuO 4 , crystals were grown at 380°C. However, the substitution of Nd by a large amount of Ce was unsuccessful.