Petroleum coke (pet-coke) is a carbonaceous solid derived from oil refinery coker units or other cracking processes. Non petroleum based cokes are made from coal.

Marketable (non power plant grades) coke is coke that is essentially pure carbon and can be sold for use as fuel, or for the manufacture of dry cells, electrodes, etc. (i.e., anode grade coke). Needle coke, also called acicular coke, is a highly crystalline petroleum coke used in the production of electrodes for the steel and aluminum industries and is particularly valuable because the electrodes must be replaced regularly. Needle coke is produced exclusively from sweet crude oil, which is in diminishing supply.

Fuel Grade Coke is classified as either sponge coke or shot coke morphology. In general, lower temperatures and higher pressures promote sponge coke formation. Oil refineries have been producing coke for well over 100 years.

Its high heat and low ash content make it an excellent carbon additive but petroleum coke is high in sulfur and low in volatile content which pose some environmental and technical problems with its combustion. This has also caused a great deal of demand for anthracite coal in order to meet current North American emissions standards.

Calcined petroleum coke (CPC) is the product from calcining petroleum coke. This coke is the product of the coker unit in a crude oil refinery. The calcined petroleum coke is used to make anodes for the aluminum, steel and titanium smelting industry. The green coke must have sufficiently low metals content in order to be used as anode material. Green coke with low metals content is referred to as anode grade coke. Green coke with too-high metals content will not be calcined and is used for burning. This green coke is called fuel grade coke. Calcined pet-coke has increasingly grown in price making it almost obsolete as more economical lower sulfur alternatives are available for iron and steel making.