steam reforming of natural gas is the most common method of producing commercial bulk hydrogen at about 95% of the world production of 500 billion m in 1998, or 70 million tonnes by 2018. hydrogen is used in the industrial synthesis of ammonia and other chemicals. at high temperatures (700 – 1100 °c) and in the presence of a metal-based catalyst (nickel), steam reacts with methane to yield carbon monoxide and hydrogen.