The biaromatic compound naphthalene dissolved in different volatile solvents has been hydrogenated over Pt/Al2O3 catalyst in a trickle bed reactor. The activity and selectivity have been investigated with various hydrogen and feed flow rates at 513 K and 5.17 MPa. The effects of partial liquid evaporization and wetting efficiency of catalyst particles on the performance of a trickle-bed reactor were studied. Experimental results and parameters calculated from the reactor model indicated that neglecting the wetting efficiency would lead to a misleading conclusion in reaction kinetics. High volatilities of feedstocks, high gas flow rate, and low liquid flow rate decrease wetting efficiencies of catalyst particles. The activity of naphthalene hydrogenation increased with increasing wetting efficiency, and the selectivity of cis-decalin decreased with increasing volatility of solvent.