About 65% of refinery hydrogen demand is met by hydrogen produced as a by-product of refinery processes. By-product hydrogen is less likely to be replaced by low-carbon hydrogen as units producing hydrogen are integral part of refining and chemical sites meeting fuels and chemicals demand. Low-carbon hydrogen is likely to replace on-purpose hydrogen if low-carbon hydrogen becomes cost competitive and policy support develops over time. Replacing fossil fuels in combustion application to generate heat and steam could provide a larger market for low-carbon hydrogen in refining. In addition to the falling costs for low-carbon hydrogen, higher carbon prices, financial incentives and stronger policy support will be necessary to accelerate its production and stimulate demand in refining. Replacement economics for low-carbon hydrogen are hugely dependent upon coal, gas, carbon and renewable power prices and hence are very refinery site and country specific.