The objective of the present report is to analyze the life cycle of mercury in the oil and natural gas value chains and understand how this heavy metal, naturally present in oil and natural gas, may be released to the environment at different stages of the process (including the decommissioning of oil and gas infrastructure), and increase mercury concentrations in the environment, presenting therefore risks to human health and ecosystems. It also aims at identifying and analyzing the management of waste from the sector, in terms of quantities produced, potential mercury emissions from the treatment phase, disposal, and where applicable, impacts of mercury recovery and reuse in the market.