There is a strong need for carbon-free and low NOx gas turbine power plants. In order to keep up with this global need, major gas turbine manufacturers are making great efforts to develop low NOx combustion technologies that can afford a high fraction of hydrogen. The purpose of this paper is to review the trends of research and development for low NOx hydrogen gas turbines carried out by major gas turbine manufacturers and research institute. Technical issues that should be considered for hydrogen combustion under wide gas turbine operating conditions will be briefly summarized, and then state-of-the-art development status for premixed-type hydrogen gas turbine combustor will be followed.