Tetrahydrofuran (THf) is a saturated cyclic ether mainly used as an organic solvent. On long term storage it forms organic peroxides. This process can be suppressed by adding butylated hydroxytoluene (BHT) as a stabilizer. BHT removes the free radicals required for the peroxide formation. THf constitutes the key fragment of various natural products (polyether antibiotics). THf can form a double hydrate with hydrogen sulfide. Crystal structure of this double hydrate has been investigated by three-dimensional single-crystal studies. Butane-1 4-diol is formed as an intermediate during the synthesis of THf. Hot THf is useful for the disSOLUTIONon of polyvinylidene chloride (PVDV).