The hydrogen burn that occurred in the Three Mile Island Unit 2 (TMI-2) accident raised a concern on the possible threat to the containment integrity of a light water reactor during a severe accident, and a great deal of analytical and experimental studies were conducted after the accident. To properly assess the hydrogen behavior in the TMI-2 accident, thermal-hydraulic response in the containment needs to be adequately described. The purpose of the present study was to estimate the thermal-hydraulic response during the hydrogen burn in the TMI-2 accident by using the CONTAIN1.1 code. It was concluded from the present analysis that the hydrogen behavior was reasonably well predicted by using CONTAIN1.1 with adequately selected set of parameters in the hydrogen burn model.