Formaldehyde diethyl acetal (FDEA, diethoxymethane, DEM) is a diethyl acetal. It has been synthesized from ethanol and aqueous formaldehyde. It is a low boiling solvent useful for sodium hydride reactions, organolithium chemistry, copper-catalyzed conjugate additions and phase-transfer reactions. It is a potential alternate for tetrahydrofuran, dichloromethane, glyme and methylal. DEM is an ethoxymethylating agent, a formaldehyde equivalent and a carbonylation substrate. Its condensation with 2-propylresorcinol to form resorcin[n]arenes (n=4–7) has been investigated. The IR and Raman spectra and conformations of DEM have been studied. NMR spectroscopy has been used to study the aggregation behavior of organolithium compounds in diethoxymethane. Unimolecular metastable decomposition of DEM upon electron impact has been studied. Solubility of non-polar gases in DEM has been evaluated.