The pyrolysis in oxygen has been studied of the common non-volatile organic acids including citric acid, malic acid, malonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and eicosanoic acid. Pyrolysates were isolated and analysed by GC/MS. The main pyrolysates of the nonvolatile acids include alkenes (from C5 to C17), aldehydes (from C2 to C17), heterocyclic compounds (furfural, 3-methyl-2,5-furandione, 2,5-furandione, 2-methyl-benzofuran), acids (acetic acid, butyric acid anhydride, an unidentified nonvolatile acid), ketones, and alcohols. All these substances can influence the qualities of aroma, taste, aftertaste, harmony and irritation of cigarette smoke.