In the present paper two fractional atomization of the oil as a way of NOx emission abatement was carried out. The suggested idea was verified by the laboratory scale investigations. As the fuel the mixture of diesel oil with additional pyridine was used to simulate the presence of the fuel bound nitrogen. The special construction of the burner was used, which allowed to change the microstructure of the atomized oil by changing the amount of primary pressured air. During these experiments authors achieved about 30 % reduction of the NOx emission. It was also ascertain, that the oil droplet mean diameter isn't the proper value for the description of the spray of burnt oil droplets as far as NOx emission is concerned.