Commodity theory of money refers to a system of money based on a specific commodity; that is, any good suitable for exchange or consumption.
The system is usually linked to a specific quantity of the commodity whose value is determined by its price in the marketplace.
The Gold Standard was a commodity money system.
M Friedman, Essays in Positive Economics (Chicago 1953), 204-50;
P Vilar, A History of Gold and Money, 1450-1920 (London, 1976)