Metallic sodium can be produced by several of the most energetic straight chemical reductions at very high temperatures, but the electrolysis of its fused hydroxide has proved cheaper than any other method, and that is the process used exclusively today.
The anhydrous hydroxide fuses at about 300° C; if the molten substance is subjected to electrolysis just above this temperature, sodium and hydrogen will be liberated in chemical equivalents at the cathode, and the corresponding amount of oxygen at the anode. The operation is carried out in small pots holding about 250 pounds of the caustic. Through such a bath, suitably provided with anode and cathode and with means to keep the gases separate, some 1,200 amperes at 5 volts will be sent. The liquid sodium collects in a receptacle at the top of the bath and is dipped out.
If sodium chloride could be used instead of the hydroxide, the metal would be much cheaper; such a process has not been perfected. It is used for chemical purposes.