The present work examines the activity, selectivity and long-term stability of platinum-promoted tungstate-modified zirconia (Pt/WO3/ZrO2) catalysts for the hydroisomerization of long-chain linear alkanes under relatively mild conditions, using n-hexadecane as a model compound. The preparation of catalysts is described. A trickle-bed reactor is used to compare the activities and selectivities of three Pt/WO3/ZrO2 catalysts prepared by different methods and to investigate the effects of tungsten loading and of reaction conditions for hydroisomerization of n-hexadecane. A run of 93.5 h was conducted using the most highly active Pt/WO3/ZrO2 catalyst which contains 0.5 wt.% well-dispersed Pt and 6.5 wt.% W. Reaction conditions were manipulated and five shutdown (feed stopped, reactor temperature lowered but H-2 flow rate maintained) and restart operations were carried out. This catalyst showed high activity and stability. Considerable success has also been achieved in converting n-hexadecane to isohexadecanes for 100 h at temperatures of about 220 degrees C and under H-2 pressure as low as 160 psig (1 psig = 6.895 kPa). Our best results (highest i-C-16 yield) are a 79.1 wt.% n-C-16 conversion, 89.9 wt.% i-C16 selectivity and 71.1 wt.% i-C-16 yield at 218 degrees C, 160 psig H-2, H-2/n-C-16 mole ratio = 2 and weight hour space velocity (WHSV) = 1 h(-1). The Pt/WO3/ZrO2 catalyst is rugged and has properties which allow one to propose that it may attain commercial use after further study.