There is growing interest in modifying USY in hydrotreating catalysts to obtain higher activity. This study provides a preliminary investigation of the interaction of titanium-phosphorus modification on USY (TiPY) and their influence on NiW-based catalyst containing USY and hydrodesulfurization (HDS) performances of 4,6-DMDBT (4,6-dimethyldibenzothiophene) and FCC LCO (fluid catalytic cracking diesel oil). Single titanium (TiY) and single phosphorus (PY) modified USY are studied simultaneously to provide further insight into how the interaction influence performance. The interaction between titanium and phosphorus on USY significantly enriched surface aluminum, and promoted the acidity and framework dealumination compared to TiY, PY and parent USY. NiW-based catalyst containing TiPY (NiW/TiPYA) had higher WS2 stacking numbers and more acidity than the catalysts containing Till or PY. The higher HDS performance was observed with NiW/TiPYA due to the synergistic effect of WS2 stacking numbers and acidity among the catalysts, where the conversion of 4,6-DMDBT and sulfur in FCC LCO was 74.3% and 98.3%, respectively. The results can provide further insight into USY modification and its influence on hydrotreating catalysts. (C) 2014 Elsevier B.V. All rights reserved.