4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is considered to be the most potent carcinogen of the TSNAs that are a class of nitrosamines that occur in tobacco products. Previous kinetics studies have shown the generation of NNK is pH dependent and temperature can affect the reaction rate from pseudo-oxynicotine (PON) to NNK. A very rapid formation of NNK from PON was measured using 200 µmole ml-1 nitrite in pH 3 buffer at 37 ºC. Nitrate and nitrite enhancement for the increase in TSNAs during warm temperature storage and moisture content is not well understood. The objectives of this study were to determine the PON and NNK changes during the storage time at four different moisture conditions. Cured ground burley tobacco which contained 7, 12, 18 and 28% moisture were stored with excessive nitrate and nitrite in separated sealed containers at 60 ºC. Nitrate level did not effect NNK accumulation in 15 days. Excessive nitrite increased NNK levels from 5.5-35X compared to controls in 15 days under different moisture levels. The greatest increase of NNK occurred with 12% moisture (~35X). PON levels were increased 4-6-fold with all moisture levels during 15 days of treatment. Measured PON increased rapidly during the first two days, especially at 7% moisture. The results indicate that NNK accumulation was altered by temperature and moisture content of tobacco.