ABSTRACT This study aims to determine the effect of the type of packaging and storage time on the chemical composition and rice cooking quality by utilizing the respiration generated heat of freshly harvested rice. “Siam Pandak” variety of freshly harvested rice stored in black plastic bag and tarpaulin with storage time of 0, 1, 2, 3, 4 and 5 days. The results showed that the accumulation of respiration heat of freshly harvested rice during storage is only capable of raising the temperature in the packaging up to 28–31 °C, slightly higher than room temperature ranging between 26–29 °C. Types of packaging and storage time could affect rice chemical composition, i.e. protein, crude fibre, fat, and carbohydrate contents. The highest protein content of 8.56% (an increase of 7.31% compared to control) was obtained by storage time of two days and the highest crude fibre content of 2.40% (an increase of 96.46% compared to control) was in the tarp packaging with storage time of five days. Fat and carbohydrate contents tended to decrease by storage time. Cooking quality was also affected by the packaging types and storage time as indicated by the increase of water absorption capacity to 298.27% (an increase of 27.74% compared to control), obtained in black plastic bag with storage time of one day. Key Word: cooking quality, chemical composition, respiration heat, freshly harvested rice