Abstract: A system for mixing hydrogen gas and air includes a housing extending from a first end to a second end and defining a mixing chamber. The second end receives the air. A tubular mixer in the mixing chamber extends along a central axis from a first end to a second end. The mixer has an outer surface and an inner surface defining a central passage. The second end is closed by an end wall. The mixer has first fluid directing structure for directing the air and the hydrogen gas radially inward from the mixing chamber to the central passage to form a mixture. A distributor is secured to the first end of the housing and receives the mixture from the first end of the mixer. The distributor includes second fluid directing structure for directing the mixture radially outward to a burner.