The research was focused on the verification of the accelerated testing method for the testing of long term catalytic activity. The verification was carried out with two types (CoMo/Al2O3 and NiW/Al2O3) of commercial HDS catalysts. The catalysts were also placed into the industrial reactor and allowed to run for approximately 16 months under the industrial conditions. Then the residual activity of the catalysts was determined. The results from the accelerated and the industrial deactivation were compared. The accelerated method included (i) the testing of the initial activity and (ii) the determination of decreasing rate of activity. The deactivation step was implemented by the injection of highly aromatic raw materials with a coking tendency. After the deactivation period the typical conditions were set (pressure 4.5 MPa, hydrogen flow 300 Nm(3)/m(3), and WHSV 1.0 kg/dm(cat)(3)). Subsequently, the reaction temperature for sulfur level 10 ppmw was determined. The implementation of accelerated method was assessed by evaluation of physical and chemical composition of the aged catalysts. The effect of coking and active phase changes on the deactivation was also described. Raman spectroscopy and SEM-EDS analyses were realized for characterization of coke deposited in the aged catalysts. (C) 2015 Elsevier B.V. All rights reserved.