Polystyrene/clay nanocomposite (PCN) was successfully prepared. Five characterization methods were applied: Particle size distribution analysis (PSD), Fourier Transfer Infrared spectra (FTIR), X-ray diffraction (XRD), Transmission Electronic Microscopy (TEM) and Differential Scanning Calorimetry (DSC). PCN was prepared by modification of Raw Kholais clay first with NaCl then with Cetylpyridinium chloride (CPC) surfactant to obtain the organoclay (OC). After ion exchange with CPC, FTIR confirmed the existence of these intercalated agents in the organic clay samples. PSD showed that the size of the monodispersed particles of Na-clay was about 1335 nm while the OC shows one peak with a narrow size distribution in the histogram of 738nm which indicate that a homogenous polymer/clay nanocomposites will be obtained. The preparation of polystyrene/OC nanocomposites was accomplished by solution blending method at different ratios of OC. They were labelled 1%, 3%, 5% and 10% NC. PCN films were characterized using XRD and TEM. Exfoliated structure was obtained for the low clay loading (1-5 % NC) while intercalated structure was probably the predominated form in the case of 10% NC. DSC showed that Tg at low clay content (1-5 wt %) decreased compared to pure polystyrene which reflected the plasticization effect of the organic modifier.