The thermal degradation behaviour of poly(isopropenyl acetate) (PIPA) has been investigated using well established thermal analysis techniques, TG, DSC and thermal volatilisation analysis (TVA), together with characterisation of volatile and involatile products. It has been shown that PIPA degrades in two main stages. The first stage of degradation, occuring between 150 and 250°C, consists of acetic acid loss which corresponds to the maximum theoretical yield. At higher temperatures, the remaining methyl substituted unsaturated backbone gradually breaks down forming a mixture of aromatic hydrocarbons that make up a slightly volatile higher fraction and relatively nonvolatile cold ring fraction. Unlike PVA, PIPA degrades almost without residue.