A comprehensive study of the regularities in the formation of active surface of WO3/ZrO2 catalysts for n-heptane isomerization was performed. The WO3 content in the catalysts (10-35 wt. %) and calcination temperature of WO3/ZrO2 (700-1000 degrees C) were found to affect the textural characteristics, phase composition, acidic and catalytic properties in n-heptane isomerization. It was shown that the catalyst with high isomerization activity comprises three phases: tetragonal zirconia (45-70%), monoclinic zirconia (20-41%), and monoclinic tungsten oxide (10-14%). The indicated phase composition can be created by thermal treatment at 850-950 degrees C of WO3/ZrO2 containing 25 wt. % WO3.