In this study, Na-montmorillonite was organically modified with cetyltrimethylammoniumbromide (CTAB) and intercalated with in-situ polymerized indene. Polyindene(PIn)/Organo-MMT nanocomposites were obtained with three different compositions and coded as: K1: [PIn(94.5%)/O-MMT(5.5%)], K2: [PIn(92.8%)/O-MMT(7.2%)], and K3: [PIn(87.9%)/O-MMT(12.1%)]. These nanocomposites were subjected to full characterization with various techniques. Electrokinetic studies were conducted to reveal the zeta (zeta)-potential characteristics of the nanocomposites. zeta-potentials of the materials were observed to decrease with increasing O-MMT content. The cationic (CTAB) and anionic (sodium dodecylsulfate) surfactants were shifted the zeta-potentials of the colloidal dispersions to more positive and more negative regions, respectively whereas nonionic surfactant (Triton X-100) caused almost no change. The pH and temperature were observed to shift the zeta-potential values of the nanocomposites to more negative and slightly more positive regions, respectively. With the addition of mono (NaCl), di (BaCl2) and three (AlCl3) valent salts, the zeta-potential of the nanocomposites were shifted to more negative, more positive, and much more positive regions, respectively. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012