<p>Motivated by the requirements for developing zero-carbon and zero-pollutant emission technology for future gas turbines, the premixed combustion of stoichiometric H₂-O₂-steam (HOS) mixtures is attracting attention; however, the combustion characteristics remain unclear. In the present study, a HOS combustion system based on a micro-mix combustion (MMC) concept is investigated, and a novel burner has been designed. Numerical models based on the RANS framework with optimized model constants and variable turbulent dimensionless numbers are validated based on experimental data. The effect of dilution ratio, jet velocity, and pressure on combustion characteristics is considered. Stable combustion with compact flames is realized and the maximum flame length is no more than 80 mm. The dilution ration has a significant influence on flames. The flame is prolonged with increasing dilution ratio. Separated jet flames are observed for most of the investigated conditions. The flame front intersection of adjacent flames occurs at high dilution ratios as combined contributions from varied chemical reaction rates and varied turbulence-chemistry interaction (TCI). The flame length increases with the increase of the jet velocity and pressure. Decreasing the jet velocity below 40 m/s will increase the risk of flashback occurring. Enhanced TCI with pressure increase offsets the decrease of laminar flame speed to some extent. The results show the reasonability of using MMC for HOS.</p>