Oxygen pump calorimeters are instruments used to gauge a reaction's heat production. They function by tracking the temperature change of a reaction mixture over time. The heat output is then determined by dividing the temperature change by the time change. These are an instrument that measures heat capacity, the heat of physical changes, or the heat of chemical reactions. Oxygen pump calorimeters are utilised in pharmaceuticals for medication design. They are used for quality control in the chemical sector and for metabolic rate analysis in biological studies.