The synergistic effect of cationic surfactant (CAB) and anionic surfactant (SDS) for the modification of Ca-montmorillonite (Ca-MMT) has been developed, and the novel cation-anion Modified organo-montmorillonite (MMT-CTAB-SDS) was prepared. X-ray diffraction (XRD) analysis indicates that the interlayer spacing of montmorillonite was well expanded by the intercalation of CTAB and SOS and the basal spacing increased from 1.54 nm (Ca-MMT) to 5.30 nm (MMT-CTAB-SDS). Thermogravimetric analysis (TG) showed that the MMT-CTAB-SDS displayed excellent heat resistance. Scanning electron microscopy (SEM) analysis proved that the MMT-CTAB-SDS exhibited excellent dispersion property and the plates with few silicate layers can be observed. Contact angle tests indicated that the hydrophilicity of MMT-CTAB-SDS was lower than that of Ca-MMT and higher than that of MMT-CTAB. It was verified that SOS contributed to expanding the interlayer space, further improved the heat resistance of the MMT-CTAB and decreased the surface energy of the MMT-CTAB-SDS particles. (C) 2013 Elsevier Ltd. All rights reserved.