Ir/FSM-16 catalysts, prepared by the impregnation method, were investigated in the selective hydrogenation of linoleic acid (cis-9, cis- 12 18:2). The results of various characterizations (X-ray diffraction (XRD), transmission electron microscopy (TEM), N-2 sorption and X-ray photoelectron spectra (XPS)) indicated that Ir/FSM-16 catalysts contain Ir particles located to a large extent within the FSM-16 channels. For the catalytic hydrogenation of linoleic acid, the Ir/FSM-16 catalyst with relatively higher Ir loading (20 wt.%) produced cis-monoenoic acids (cis 18: 1), while dienoic isomers mostly with trans configuration were predominantly produced over Ir supported on Don-porous SiO2. The cis/trans ratio of monoenoic acids for the former catalyst was four times larger than that for the latter catalysts. The observed stereoselectivity may be due to an inhibition of the geometric isomerization by the limited space between Ir particles and pore wall of FSM-16.