A novel class of cationic gemini surfactants were prepared and used as modifiers for sodium montmorillonite (MMT-Na). The modified montmorillonites were characterized by X-ray diffraction (XRD), thermal analysis (TG), Fourier transform infrared spectroscopy (FTIR), dispersibility measurement, and scanning electron microscopy (SEM). The results show that the surfactants have been intercalated into the montmorillonite layers successfully. XRD measurements indicate that the gemini surfactant is more effective at expanding the interlayer space of the MMT than the corresponding single chain surfactant. Moreover, the high efficiency can be obtained by lengthening the hydrophobic chains of gemini surfactants. Thermal analysis shows that there are four different molecular environments for gemini surfactants in the modified montmorillonite. The dispersibility measurement and SEM results indicate that the modified montmorillonite are more hydrophobic and prone to agglomerate in water than MMT-Na. These modified materials have the potential for removal of environment pollutants such as pesticides, phenol, etc. or being used as antimicrobial materials. (c) 2008 Elsevier Inc. All rights reserved.