Heat-recirculating combustion by regeneration produces high-temperature flames and emission of nitric oxides increases with the flame temperature. This is the main reason why reduction of nitric oxides is essential to give the high thermal efficiency of regenerative combustion systems. However, in this work, combustion takes place even though the combustion air is diluted with burnt gases until its oxygen concentration becomes as low as 1 or 2% by use of combustion air pre-heated to a temperature higher than the auto-ignition temperature of the fuel. These unexpected conditions were used to reduce the emission of nitric oxides because the associated temperature rise due to combustion was considered relatively small. Thus, innovative combustion technology, in which both high thermal efficiency and low nitric oxides emission can be achieved simultaneously, is possible.