What role do hydroxyl radicals play in hydrogen combustion?

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In the context of hydrogen combustion, hydroxyl radicals (•OH) serve as critical intermediates within a complex branched-chain reaction mechanism.1

The process unfolds through the following stages:

Formation: Hydroxyl radicals are produced when hydrogen and oxygen atoms interact with oxygen and hydrogen molecules, respectively.1
Product Generation: The final product of the combustion, water, is formed when these hydroxyl radicals combine with hydrogen molecules.1

Because hydrogen combustion relies on these branched-chain reactions, the behavior of hydroxyl radicals and other active particles is essential to determining the characteristics of the combustion process, including burning velocity, ignition delay, and explosion limits.1