ZSM-5 zeolite was mixed with Al(OH)(3) (1:1) and modified with Ni from aq. soln. of Ni(NO3)(2) (calcination at 480 degrees C for 3h) to produce NiO(8%)/ZSM-5+Al2O3 catalysts (8 wt.% NiO) differing in the methods of combining Al2O3 and zeolite and of Ni incorporation. The Ni catalysts were then modified with Ru acetylacetonate (0.6-0.9 wt.% RuO2). The spent RuNi catalysts after hydroconversion of diesel oil fraction were examd. by the temp.-programmed oxidn. method. The incorporation of 0.6 wt.% RuO2 into the Ni catalyst resulted in a decrease of coke formation by approx. 3 wt.%, and in an increase of the H/C at. ratio in the deposits. The rise in RuO2 from 0.6 to 0.9 wt.% noticeably facilitated the coke oxidn. The oxidability of the coke deposited on the RuNi catalysts depended on the method for their prepn.