Evaluation of opportunity to raise Euro V diesel production by increasing fluid catalytic cracking (FCC) light cycle oil (LCO) production was carried at the Lukoil Neftochim Bourgas, Bulgaria (LNB) refinery. The FCC LCO (IBP-360 degrees C) production was investigated in the FCC conversion range between 69 and 83 wt.% and LCO initial boiling point (IBP) between 177 and 210 degrees C. It was found that the LCO yield increased from 16.0 up to 20.7 wt.% by decreasing conversion from 83 to 69 wt.%. At constant conversion in the FCC unit of 79.7 wt.% the LCO yield increased from 17.8 to 24.8 wt.% by decreasing the IBP from 210 to 177 degrees C. A further 3.5 wt.% LCO yield increase and meeting the diesel flash point specification of 55 degrees C can be achieved by lowering the LCO IBP down to 163 degrees C. It was found that during hydrotreatment of a blend of the LNB middle distillates and LCO in a high pressure (70 bars) hydrotreater employing Co-Mo catalyst the maximum LCO (IBP = 210; FBP = 300 degrees C) content that allows meeting the EN specifications is 10 wt.%. If the LCO IBP is reduced to 177 degrees C then the maximum LCO content in the feed can reach 20 wt.%. The limitation of density not higher than 0.845 g/cm(3) in the hydrotreated product at 15 degrees C is the restriction for further increase of LCO content in hydrotreater feed. Replacing the Co-Mo catalyst by Ni-Mo and noble metal catalysts in the high pressure hydrotreater can allow more than double increase of LCO content in hydrotreater feed. Hydrogen chemical consumption in that case, however is also more than twofold. (C) 2012 Elsevier B.V. All rights reserved.