Abstract: A decomposition inhibitor for hydrochlorofluorocarbons and hydrofluorocarbons (HCFCs/HFCs) which comprises at least one member of the class consisting of organic acid-amine mixtures, fluorine-free halogenated hydrocarbons, carboxylic acid esters, nitrile compounds, carbonyl compounds and halogenated nitro compounds. A method of inhibiting the decomposition of HCFCs/HFCs which comprises using the decomposition inhibitor mentioned above.In the field of polyurethane foam manufacture using HCFCs/HFCs as blowing agents, the effect of inhibiting the decomposition of HCFCs/HFCs can be produced over a long period of time covering the storage of raw materials, the foam manufacturing process and the use of foamed products.