High Quality Content by WIKIPEDIA articles! An Ellingham diagram is a graph showing the temperature dependence of the stability for compounds. This analysis is usually used to evaluate the ease of reduction of metal oxides and sulphides. These diagrams were first constructed by Harold Ellingham in 1944. In metallurgy, the Ellingham diagram is used to predict the equilibrium temperature between a metal, its oxide and oxygen, and by extension, reactions of a metal with sulphur, nitrogen, and other non-metals. The diagrams are useful in predicting the conditions under which a metal ore will be reduced to the metal. The analysis is thermodynamic in nature and ignores reaction kinetics. Thus, processes that are predicted to be favourable by the Ellingham diagram can still be slow.