The sodium‐sulphur battery is reviewed and experimental results are presented. The experimental cells were capable of delivering steady state power densities as high as 50 W.kg−1 and energy densities as high as 250 W.h.kg−1. The theoretical open circuit voltage of 2.08 V was observed in all cases. Cell polarization was limited by cell internal resistance, which was attributed largely to the resistance of the β‐alumina electrolyte. The “asymmetry effect” is explained in terms of an electrode blockage mechanism involving polysulphides. The sodium‐sulphur battery appears to be technically feasible as the power source for an all‐electric vehicle.