A nitric oxide gas generator which includes a body having a dilution inlet chamber, a chemical mixing chamber, and a dilution outlet chamber. A dilution inlet for diluent gases is provided into the dilution inlet chamber. An inlet is provided to permit entry of the diluent gases into the chemical mixing chamber. An outlet is provided to permit the exit of diluted nitric oxide gas from the chemical mixing chamber to the dilution outlet chamber. A dilution outlet is provided for removal of diluted nitric oxide gas from the dilution outlet chamber. Supports are provided for supporting chemicals to be reacted to produce nitric oxide gas. A heat source is provided to heat the chemical mixing chamber in which chemicals are mixed to initiate a chemical reaction that produces nitric oxide gas.