Abstract: A precision static oxygen bomb combustion calorimeter with thermistor thermometer was constructed in this laboratory. The experimental data was treated with electronic computer, the programme was designed by ourselves. The calorimeter was calibrated with benzoic acid of purity 99.999 percent, its energy equivalent is 12.6028±0.00114 kJk~(-1). Using this calorimeter, the standard energy of combustion of tris (hydroxy-methyl)-aminomethane (THAM) at 298.15 K was measured, its value was Δ_cu~°=-20.0303±0.0060 kJg~, in satisfactory agreement with that cited in literature (-20.0303±0.0034 kJg~(-1)), the reliability of this apparatus wa confided.