We report a study on the synthesis of a nanocomposite that contains anatase titania (TiO₂) particles, organo-montmorillonite (OMMT) and cellulose-g-poly(methyl methacrylate) (cellulose-g-PMMA), and the application of the nanocomposite as a photocatalyst in degradation of 2,4-dichlorophenol (2,4-DCP). The nanocomposite was characterized by Fourier-transform infrared spectra, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The photocatalytic activity of the nanocomposite was evaluated by the photoreaction of 2,4-DCP. We compared the photocatalytic activity of the nanocomposite in the presence or absence of OMMT, PMMA and TiO₂. The photocatalytic activity of the nanocomposite was also compared with commercial TiO2 nanoparticles. The synthetic nanocomposite exhibits the highest photocatalytic activity. After the fourth time recycling, the nanocomposite still maintains more than 90 % of its photocatalytic activity.