A microporous silica/FeOn catalyst was prepared by calcination with poly(vinyl alcohol) (PVA). The surface area of the catalyst increased with the content of PVA in original composite. Because of the cylindrical shape of the pore, it was assumed that in the composite PVA chains existed in bundles of 20-30. The silica/FeOn composite showed catalytic activity for H-2 isomerization. The rate of isomerization followed first-order reaction kinetics and the activity increased almost proportionally to the surface area, which corresponded to PVA content in the original composite. The Arrhenius plot showed a positive slope, in contrast to ordinary reactions. The activation energy was apparently -2 kJ/mol. This result is explained on the basis of the paramagnetic susceptibility of FeOn, which decreases with increasing temperature.