Carbon neutrality is now important and inevitable in the 21st century for climate change and global warming, and numerous industries are trying to decrease the emission of greenhouse gases. Also, numerous studies have been followed in the steel industry, and FINEX was first devised and is now used as decreasing 20 % of greenhouse gases during the production of iron. Furthermore, the HyREX that is the production process of direct reduced iron with hydrogen was devised for carbon neutrality by replacing coal with hydrogen. In this study, HyREX was studied for its temperature and the number of cycles with 7 % of hydrogen by simulation using Chemical equilibrium with applications to find optimized conditions since it is challenging to research as an experimental approach due to the problem of cost and size. The optimized condition was defined as the point that reduces all oxygen from iron ore because the rest of iron ore or oxides can cause the problem of purity. The temperature range was set between 800 K to 1200 K as known temperature for the production of direct reduced iron that is below the melting point of iron. The amount of provision of iron was constant as 100 g and the percentage of hydrogen was based on the weight. As a result, 69.942 g of direct reduced iron was produced with 100 g of iron under 1200 K of temperature and 5 cycles with 7 % of hydrogen.