For the first time, emission of alkali vapor species from biomass is being directly observed, under combustion conditions, by molecular beam mass spectrometry. The free jet sampling system cools the products of combustion extremely rapidly with little condensation, making it possible to identify the alkali species that are active in high-temperature vapor transport. Recent results are discussed in light of the mechanisms of release and the implications for the use of biomass in gasification and combustion systems. The paper also includes a substantial review of literature relative to alkali in biomass and its behavior vis-a-vis coal.