The adsorption of dodecyldimethylamine N-oxide into the interlayer space of Na-saponite was investigated. The Na-saponite/dodecyldimethylamine N-oxide intercalation compounds were prepared as supported and unsupported films. Intercalation compounds with two different arrangements of the intercalated dodecyldimethylamine N-oxide were obtained, depending on the adsorbed amounts. When the adsorbed amount was greater than 400 mmol/100 g of clay, the intercalated dodecyldimethylamine N-oxide took a paraffin type bilayer. On the other hand, the intercalated dodecyldimethylamine N-oxide molecules are thought to arrange as a bimolecular coverage with their alkyl chains parallel to the silicate sheet when the added amount of dodecyldimethylamine N-oxide was 100 mmol/100 g of clay. The coadsorption of tris(2,2‘-bipyridine)ruthenium(II) with dodecyldimethylamine N-oxide was achieved. The luminescence characteristics of tris(2,2‘-bipyridine)ruthenium(II) revealed that there are certain interactions between the adsorbed tris(2,2‘-bipyridine)ruthenium(II) and dodecyldimethylamine N-oxide in the interlayer space of saponite. Since the products have been obtained as highly transparent supported and self-standing films, the intercalation of dodecyldimethylamine N-oxide is a way to control the adsorbed states of cationic dyes on the surface of smectites.