This thesis reports exploratory studies on the synthesis and characterisation of new compounds as cathode materials for second generation sodium batteries, with a particular emphasis on preparing new iron-phosphite and molybdenum oxyfluoride cathode materials. Seven different compounds are hereby reported: the sodium iron fluoro-phosphite of formula NaFe₃(HPO₃)₂[(H,F)PO₂OH)₆], the iron-phosphite Fe₂(HPO₃)₃, the sodium iron-phosphite NaFe(H₂PO₃)₄, the sodium iron phosphate NaFe(HPO₄)(H₂PO₄)₂·H₂O and three molybdenum oxyfluoride compounds of formula Na₂MoO₂F₄, KNaMoO₂F₄ and KMoO₂F₃. The synthesis of these compounds was performed by hydrothermal and solvothermal methods at temperatures ranging from 100 °C to 160 °C. The compounds were then fully characterised using the following techniques: single crystal X-ray diffraction (SXD), powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), elemental analysis (EA), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and electrochemical testing. Magnetic properties have also been studied where appropriate.