The radioactivity of 3 H of metal samples from nuclear sites was analyzed by using a commercialized high temperature furnace and a liquid scintillation counter (LSC). The 3 H activity of a sample was measured according to the duration of the high temperature combustion and the oxidation temperature. Basically, the recovery from the furnace was 90% for 3 H, and the LSC had a counting efficiency of approximately 30%. HNO 3 was used as a trapping solution for 3 H, and the scintillation cocktail was added for LSC measurement. The activity of the metal sample was increased till the combustion time of 60min had elapsed and decreased continuously thereafter at 600°C whereas most of radioactivity was extracted during the first 15min at 900°C. Also, the pre-treatment of the metal sample, which included a high temperature combustion and trapping, had the time required of at least 4h at 900°C. Finally, it was suggested that this high temperature combustion method could be applied to analyze the activity of the radioactive metal waste from nuclear power plants for the determination of its clearance.