A coke oven is a device used to produce coke, which is derived from coal. The mixing and heating of bituminous coal at temperatures ranging from 1,000 to 2,000 degrees Celsius within the airless coke oven yields the coke byproduct. The coke oven is a crucial part of the coke-making process.

Coke is a solid remainder of combusted carbonaceous material. It also contains a minor quantity of ash and sulfur. Coke can be used as a fuel or as a reducing agent in blast furnaces used for the smelting of iron ore. It is generally considered to be one of the three fundamental materials for producing iron, which is then used to make steel, usually in combination with limestone and iron ore. The gasses from the coke oven may also be used as a fuel.

Most coke ovens produce coal by heating coal under controlled circumstances. As the absence of oxygen is important to yielding the best quality coke, coke ovens are designed as airless ovens. They may also be arranged in batteries and strategically situated between heating walls. This can increase coke production and the efficiency of the coke oven.

In the coke-making process, treated coal is placed in the coke oven. Due to the high temperature inside the coke oven, coal gas, coal water, and tar are separated from the coal. The coal gas and coal water then fuse together with carbon and the remainders of ash. The hard residue that remains at the end of this process is commonly referred to as coke.

The coal used for selection in the coke-making process is often an important part of the procedure. Coal may be selected according to factors such as ash and sulfur content, tar, plasticity, and volatility. The volatility of coal can be important, since it will allow for a greater quantity and higher quality of coke to be produced. This is because the more volatile the coal is, the more byproducts it will yield. However, too much volatility of coal can be a negative, as the byproducts become too porous for making quality coke.

Emissions of coke ovens have been shown by some studies to be dangerous to humans; this has led to the emissions being identified as human carcinogens. These studies have shown a correlation between the exposure of workers to coke ovens and instances of types of cancer such as lung and intestinal cancer. Tests done on the skin of animals, like mice, also have demonstrated that exposure to coke ovens may produce malignant tumors.