A distorted square-pyramidal N2S3-type Co(III) complex with a vacant site was previously synthesized as an active site model of Nitrile hydratase (NHase), and the coordination behavior of a water molecule to the vacant site was discussed. In this paper, the coordination of other monodentate ligands (CN-, tBuNC) to the complex was studied using UV-vis and IR spectral measurements. The UV-vis spectra changed with isosbestic points at ca. 300 nm and 370 nm by addition of CN- or tBuNC. The IR spectra showed C≡N stretching vibrations at 2112 and 2197 cm-1, respectively, both of which are different from those of the respective metal-free ligands, CN- (2069 cm-1) and tBuNC (2135 cm-1). These results indicate that CN- and tBuNC can coordinate to the vacant site of the Co(III) complex. Furthermore, we tried the adsorption experiments of the complex into FSM (folded-sheet mesoporous metarial) with hydrophobic mesopores. The adsorption amount of PPh4[Co(L1-O4)] for FSM exhibited a high value of ∼40 w/w% in CH2Cl2, although such an adsorption behavior was not observed in MeOH.