Stannic oxide SnO₂ nanoparticles were tailored using sol-gel approach, in which stannic chloride pentahydrate SnCl₄.5H₂O utilized as an inexpensive starting material. The obtained gel is dried then calcined at 450^oC to form tetragonal SnO₂ structure (6.0 - 8.2 nm). The obtained powders are doped with different loading 10-55 wt. % of HF as a source of fluoride ion, followed by calcination at 200, 300 and 400^oC. The surface acidity is examined for the fabricated samples with nonaqueous potentiometric titration versus n-butyl amine in acetonitrile. Surface acidity measurement results indicate that 45F-Sn contains the strongest acid sites. The calcination temperature 200^oC is the ideal appropriate temperature for calcination at that the overall surfaces acidity and the acid strength reach to their maximum values. The catalytic efficiency was examined via solvent-free synthesis of 14-aryl-14H dibenzo [a,j] xanthene. 45F-Sn calcined at 200^oC shows the highest catalytic activity and gives an excellent yield about 95.63%.