Abstract: The rate of concentration variation of 25% ascorbic acid injection in anaerobic degradation was studied at 98, 90 and 80℃. These degradations were found to be of pseudo-zero order reactions, with somewhat varying rate constants of degradation when the concentrations of the injection were greater or less than about 85% of the initial concentration. The rate of concentration variation of 5% ascorbic acid injection at 98℃ and that of 12.5% ascorbic acid injection at 90℃ in anaerobic degradations were studied for comparison. These degradations were found to be pseudo-first order reactions, with somewhat varying rate constants of degradation when the concentrations of the injection were greater or less than about 75% of the initial concentration. The anaerobic degradation at 98℃ of 25% ascorbic acid solution, not containing antioxidants, was found to be a pseudo-zero order reaction too.