Light cycle oil (LCO) and waste sunflower cooking oil (WSO) were co-processed with the aim of obtaining more environmentally friendly fuels. Partial hydrogenation of naphthalene was also investigated as a model reaction. Commercial NiW/SiO2-Al2O3, as a reference catalyst, and NiW/(pseudoboehmite + SBA-15), as a new research catalyst, were tested. Liquid products were analyzed by simulated distillation, elemental analysis, and FTIR spectroscopy. Elemental analysis indicated higher efficiency of the research catalyst in hydrodesulfurization, hydrodenitrogenation, and hydrodeoxygenation of pure LCO and mixed feedstock containing WSO. Reactions with pure WSO resulted in less sulfur leaching into the product and a lower degree of deoxygenation compared with the commercial catalyst.