Commercially available smectite clay (bentonite) was modified by ion exchange reaction usingN-Cetyl-N,N,N-trimethylammoniumbromide (CTAB) to prepare organophilic clay. The reaction was carried out in acidic medium (conc. HCl) under controlled stirring at a temperature of 80ºC for a specific period of time. Physico-chemical and thermal properties of the clay before and after modification were determined and compared using X-ray diffraction (XRD), Fourier transforminfra red (FTIR) and thermogravimetric analyzer (TGA). The chemical composition of bentonite was determined by Xray fluorescence (XRF) and the cation exchange capacity (CEC) of the clay was determined bymethylene bluemethod. The CEC value is found 29meq/ 100g of the sample and the XRD analysis showed the enhancement of basal spacing from12.2 Å to 12.9 Å after themodification of the clay. The results revealed that desired modification of bentonite has been achieved.