At different time intervals, photo-oxidative degradation of organically modified montmorillonite (OMMT):viton rubber composites were studied under accelerated UV (aeyen290 nm) irradiation. The changes in properties (mechanical, thermal, and physical) before and after UV exposure were studied using universal testing machine (UTM), thermogravimetric analyzer (TGA) and shore A hardness tester. Meanwhile, surface of montmorillonite (MMT) was modified using column chromatography technique (quaternary long chain ammonium salt as an intercalent), which resulted in uniform exchange of ions between MMT and ion exchange resin; and thus d-spacing increases to 31.5 . Viton:OMMT nanocomposites were prepared using two roll mill and compression molding machine to obtain a square sheet. Prolonged exposure to UV leads a progressive decrease in mechanical, thermal and physical properties along with the change in behavior of filler-matrix interaction, which was due to decrease in cross-linkage density with increase in the mobility of rubber chains. The increases in carbonyl (> CO), hydroxyl (-OH) functional groups after degradation of OMMT:viton rubber composites at different time intervals (0, 100, 200, 300 h of UV exposure) were studied using Fourier transform infrared spectroscopy (FTIR). Besides this, the change in surface behavior of viton rubber composites before and after degradation was studied using scanning electron microscopy (SEM). Overall, the study shows that the OMMT:viton composites were affected more upon irradiation compared to pristine viton composites and it was more prominent at 12 wt% loading of 300 h of UV exposure.