Iron and steel industry lays foundation for export industries in Thailand. Currently, Thailand can produce only low grade steel since it does not have primary production itself. Therefore, proposals were made by private sectors to set up primary iron and steel production plants. Globally, primary iron and steel industries were well recognized for their high consumption of natural resources as well as high emission of pollutants, especially greenhouse gases. The aim of this study was to indicate procedures for emission reduction target setting for iron and steel. The data gained may be used in international negotiating arena. Another goal of this study was to determine potential for greenhouse gas reduction for Thailand iron and steel industries. This would cover appropriate measures for capabilities improvement in both with and without primary iron and steel production. In this work, we reviewed production technologies, current emission situations, and greenhouse gas reduction technologies. We also surveyed industries and interviewed experts as well as stakeholders in academics, governments, and private sectors. Furthermore, calculation and assessment of greenhouse gas emissions, reduction potentials, and relating costs in the cases of no primary iron and steel, primary iron and steel with advanced technology (pilot scale BAT), and primary iron and steel with moderate technology (commercially available BAT), was performed. Greenhouse gas emission from iron and steel industries was related with energy consumption. Three major sources of emission were identified: chemical reactions, fossil fuel combustion, and electricity consumption. Overall world greenhouse gas emission from iron and steel industries was at 1.7 ton CO2 /ton crude steel. This number was a weighted average value from major steel production routes, namely, BF-BOF, OHF and EAF. China was found to be a major emitter and released around 900 tons of CO2 in 2006 from steel production of approximately 422 million tons. Popular GHGs emission indicator was CO2 emission per ton product since it did not interfere with production volume. Emission target setting relied heavily on raw data, if possible, at factory level. This was to be done ahead. Steps for target setting should begin with emission database, projected emission, and possible reduction potential that would not harm country competitiveness. Current iron and steel industries in Thailand was in mid- and downstream level. Major emissions were from electricity production (59.26% of total emission) rather than direct ones. Average emission was 321.66 kg CO2 equivalent/ton product. Total emission for overall iron and steel industries was 2.82 million ton CO2 equivalent. Without primary iron and steel industries, CO2 emission would be 6.25 million ton CO2 equivalent in 2563. With advanced BAT iron and steel industries, Thailand would release 13.18 million ton CO2 equivalent in 2563. With commercially available BAT iron and steel industries, Thailand would release 15.54 million ton CO2 equivalent in 2563. Maximum reduction for the case without primary iron and steel would be around 6%. In the case with primary steel production, highest emission was obtained from carbon capture and storage-CCS, which was around 29-31% reduction from BAU. Urgent measures for emission target setting and improvement of reduction potentials were such as clear assignment for responsible parties, collection of data by approved and appropriate procedures for National registry, involvement of all stakeholders, addition of BAT in the investment promotion guidelines, as well as considerations to support production sectors both technically and financially.