Root cause analysis of premature failure of a boiler tube of a captive power plant is presented in this paper. The boiler tripped on high pressure. The investigation showed that the boiler tube suffered localized corrosion on the water side (inner wall) of the boiler tube. Copper was found to have deposited at the leaked area. Possible corrosion of the cupronickel condenser releasing copper ions into the condensate and their subsequent deposition in the boiler tube seem to have aggravated to localized corrosion attack. The situation seems to have further aggravated as the company changed from coordinate phosphate treatment to all volatile treatment for the water. No evidence of (a) caustic or hydrogen embrittlement and (b) decarburization due to localized heating was found. Several recommendations such as cleaning the boiler to remove copper deposits, addition of oxygen scavenger, checking and cleaning condenser unit were made to avoid recurrence of the failure.