Abstract. Ogunsanwo OY, Onakpoma I, Korede M. 2020. Thermal properties of wooden based flask from tropical hardwood species. Asian J For 4: 61-64. Most materials used for production of conventional thermos flask (metals and plastics) are not environment friendly with particular concerns about plastic which are not biodegradable. Wood waste management is important in producing environmentally friendly materials and achieving sustainable development in forestry through wood waste utilization as thermos flask. This study was therefore conducted to investigate the thermal properties of wooden thermos flask (WTF) using tropical hardwood species with a view to promoting the use of greener technology. Offcuts of Tectona grandis and Albizia saman were used to produce 12 WTF of two thicknesses (11 mm and 12 mm), with a height of 10.5'' using bamboo as inner lining. The heat loss and heat gain by the wooden flasks and conventional flask were collected using a thermometer which was inserted into the cap of the flasks through a hole drilled in it, the hole was covered at intervals to prevent heat loss and heat gain from the opening. Data was collected every two hours for twelve hours. The study was laid out in a 2×2 factorial experimental in a completely randomized design. Data were analyzed using ANOVA at p=0.05. The highest heat loss (64.00ºC) after 12 hours was observed in Tectona grandis WTF with 11 mm and 12 mm while Albizia saman thermos flask with 12 mm thickness had the least heat loss (62.00ºC). Metallic flask lost only about 30.00 ºC of its heat content after 12 hours. The highest heat gain (28ºC) after 12 hours was observed in Tectona grandis WTF with 11mm and 12mm while Albizia saman WTF with 11 mm thickness had the least heat gain (25.67ºC). Heat gained by WTF was 28.00ºC and 25.83ºC for Tectona grandis and Albizia saman respectively after 12 hours while heat gain by the metallic flask after 12 hours was 18.00ºC. Species and thickness did not significantly affect heat loss and gain of thermos flask. Significant difference was however observed between the heat lost and gained by WTF and metallic flask. Wooden thermos flask still retained heat and prevented loss to a certain degree but technological improvement would perform better.