Most manganese used in the world is consumed as ferroalloys by the steelmaking industry. Submerged arc electric furnace smelting using the manganese-rich slag method is widely used to produce ferromanganese. This process has been modelled using the HSC computational thermodynamics package. It was assumed that higher manganese and iron oxides are reduced to MnO and FeO before entering the zone where molten slag and alloy form and equilibrate. The model predictions were compared to data from Thermit Alloys (P) Limited, an Indian ferroalloy smelter, and the agreement was found to be good. It was then used to examine the affects of changing the amount of carbon reductant and temperature on several performance indicators. The results of this modelling are discussed and it is concluded that the model is useful as an aid to understanding ferromanganese smelting.CO CO2 = 1 whereas Fe 3 O 4 reduction to FeO requires either carbon or a gas mixture with a higher CO(g)