The development of catalysts possessing high activity and high stability in the catalytic hydrotreatment of pyrolysis oils (bio-oil) is of great interest. NiCu bimetallic catalytic systems are very attractive for use in hydrotreatment process due to their low price and high activity in hydrogenation, hydrodeoxygenation and hydrocracking reactions. In the present work P-/Mo-containing agents were used to modify bimetallic catalytic system NiCu/SiO2-ZrO2 to improve its mechanical strength and stability in acidic medium. The modified catalysts were tested in hydrodeoxygenation (HDO) of guaiacol-a well-known model compound of bio-oil. HDO process has been carried out in an autoclave at 320 degrees C, 17 MPa initial hydrogen pressure, reaction time 1 h. It was shown that phosphorus and molybdenum addition to the catalysts composition results in the decrease of guaiacol conversion and deoxygenation degree. The yield of undesirable gaseous reaction products (mainly methane) and coking of the catalyst were lower for the modified catalysts in contrast to the initial NiCu/SiO2-ZrO2 system. The catalysts treatment in glacial acetic acid at 118 degrees C showed that modification by P and Mo gives a significant improvement of catalysts stability in acidic medium (mass loss decreases from 53 wt.% to 1 wt.%). Also a significant improvement of bulk crushing strength has been observed for PMo-modified samples (from 0.5 MPa to 1.2 MPa). (C) 2013 Elsevier B.V. All rights reserved.