Thermax Limited (Thermax) came to business in 30th June of the year 1980, operating out of its headquarters in Pune, India, Thermax delivers comprehensive solutions in sustainable solutions in Energy and Environment by the way of standard products in the 6 areas of business, such as Boilers and Heaters, Absorption Cooling, Water and Waste Solutions, Chemicals for Energy and Environment applications, Power and Cogeneration systems and Air Pollution and Purification Thermal's international operations are spread over South East Asia, Middle East, Africa, Russia, UK and the US.

Tulsi Fine Chemical Industries Private Ltd and Kailas Castings Private Ltd were merged with the company with effective from 1st July of the year 1982. As at 1st July 1989, Thermax became a deemed public company. In the year 1991, T. K. Steel Industries Ltd was merged with the company. During the year 1994, the company's status was changed from deemed public company public company. The process heat division came out with a new boiler design in the year 1995, an oil fired smoke boiler, shell Max and Combiac, a boiler specially designed to burn agro fuels like rice and groundnut husk, saw dust, coffee waste etc. also in the same year of 1995, a Memorandum of Understanding (MoU) was signed with Bharat Shell for thermic fluid, therma, for heat transfer system. The process heat projects division received an order from PT South Pacific Viscose, an Indonesian Company for supply of 3 boilers of 22.5 tonnes per hour of steam. Energy System Division of the company was born in the year 1996 by the way of merger of two division, one in the energy area and the other in heat recovery area to pool the expertise with a view to addressing the heat recovery business and also in the same year formally introduced fine circulation fluidised bed combustion boiler. The MoU was signed with Bharat Shell and the Process Heat Division of the company.

During the year 1997, the company had received the AD-Merkblatt certification for the entire manufacturing unit at Chinchwad. An electronic network called Thermnet linking all establishments of the company in the country was introduced during the year same year of 1997 and also Thermax had broadened its footprint operations into into a joint venture with Fuji Electric Company of Japan. The Company had introduced five new products in the standard packaged boiler range during the year 1998 and also formally introduced a wide range of products incorporating Kawasaki modular technology in our Vapour Absorption Division. Thermax Co-gen Limited became a subsidiary of the company in the year 1999. During the same year 1999, the company had successfully engineered a more advanced process called PDP II. During the year 2000, Thermax had executed a strategic acquisition of ME Engineering, a UK-based company belonging to the Beel Industrial Boilers Plc group. The Company has signed an exclusive distribution agreement for South Asian markets with US company Purafil Inc to market their dry gas scrubbers popularly widely referred to as chemical filters. Thermax had signed a memorandum of understanding with the Society of Applied Microwave Electronics Engineering and Research for commercialisation of the latter's microwave disinfections system for treating pathological bio-medical waste generated by hospitals and research institutes. The Company had created and deployed wholly owned subsidiary company in the US, namely Thermax Inc and another one in Detroit, USA in the year 2001. Thermax had executed a strategic acquisition of 50% of stake in Energy Performance Service (Thailand), a subsidiary of Energy Performance Service of Canada. The Company and Cummins Diesel Sales and Services had broadened its footprint operations into into a strategic alliance to provide attractive energy solutions to various industry segments.

With the investment of US $ 200,000, the company had incorporated a wholly owned overseas (WOS) subsidiary in Brazil during the year 2003. Thermax had bagged an order for Captive Power Plant in the year 2004. During the year 2004-05, the company's chemical plant at Paudh, near Mumbai had received the OHSAS 18001:1999 certification from BVQI. COFEX 2005 honored with special award for Thermax's contribution to the HVAC industry. Thermax had inked a technical know-how transfer and license agreement with Balcke-Durr, Germany in October of the year 2007 for dry and wet electrostatic precipitators (ESPs), air pollution control equipment for power, industrial and utility segments upto 300 MW.

As at February 2008, the company had signed a technical transfer license agreement with US-based Babcock & Wilcox Power Generation Group (B&W) to engineer, manufacture and sell sub critical B&W radiant utility boilers in India. As of May 2008, the company had inked a protocol of agreement for an export order, for supply of heat recovery steam generator (HRSG). Thermax had received an order from a major refinery in July of the year 2008, to supply pulverised coal fired boilers for their captive cogeneration plant valued at approximately Rs 8.2 billion and also in August of the same year 2008, received an order of Rs 4.15 billion, from a leading steel making company in August pf the year 2008, for setting up a captive power plant for their upcoming blast furnace complex on an EPC basis.

Thermax is planning to created and deployed a new Rs 5-billion manufacturing plant for large boilers of capacity 100 mw to 800 mw for power plants. In the first phase, the company will have a capacity to produce sub-critical boilers with total capacity of 1,500 mw per annum, which would entail an investment of Rs 3 billion. In the next phase the company will scale up the capacity of the boilers of equivalent to 3,000 mw with an additional investment of Rs 2 billion.