In this work ZrS₃ has been synthesized by solid state reaction in a sealed quartz tube and investigated as a candidate cathode material in Li thermal batteries. The structure of ZrS₃ before and after cell testing has been studied using powder X-ray diffraction. A new spinel related material, LiZr₂S₄, has been identified as the product of the electrochemical process, which can be indexed to a = 10.452(8) Å cubic unit cell. The electrochemical properties of the batteries were investigated at 500 °C against Li₁₃Si₄ by galvanostatic discharge and galvanostatic intermittent titration technique (GITT). In a thermal Li cell at 500 °C a single voltage plateau of 1.70 V at a current density of 11 mA/cm² was achieved with capacity of 357 mA h g^-1. Therefore ZrS₃ material has some promise as a cathode for Li thermal batteries.