<p> This thesis is concerned with the determination of the thermodynamics of the Fe-V-O system. </p> <p> In the first part the thermodynamics of liquid Fe-V-O alloys were studied in the temperature range of 1550-1700ºC using H₂O/H₂ equilibrium and/or an oxygen probe. 1st and 2nd order interaction parameters between V and O were determined, and the deoxidation reactions occurring when V is used as a deoxidizer were studied. Deoxidation diagrams are presented for V concentrations up to 12 wt. %. </p> <p> In the second part the thermodynamic equilibria between the lower oxides of vanadium (V - VO₀ٜ₂₋ₓ, VO₀ٜ₂₊ₓ - VO₁₋ᵧ, VO₁₊ᵧ - VO₁ٜ₅) were determined in the range 800-1400ºC using a solid state EMF technique, and the free energy of the formation of the oxides VO₀ٜ₂₊₍₋₎ₓ, VO₁₊₍₋₎ᵧ, VO₁ٜ₅ was estimated. </p> / Thesis / Doctor of Philosophy (PhD)