The company's net profit in the year-ago period was Rs 86.01 crore, Thermax said in a regulatory filing.
Total income of the company during the period decreased to Rs 1,069.62 crore from Rs 1,180.31 crore in the year-ago period.
"As on September 30, Thermax has an order backlog of Rs 4,006 crore against Rs 5,016 crore in September, 2014," the company said in a statement.
Thermax Ltd, a leading energy and environment solutions provider, has manufacturing facilities in India, China and Europe.