Influence of light represented by ultraviolet radiation having two different wavelengths, ٢٥٤ nm and ٤٠٠ nm, on some Iraqi cellulose extracted from reeds as a raw material has been studied. It was found that the natural degree of polymerization of cellulose fibers was affected by UV radiation. This was estimated by measuring the relative viscosity of cellulose solution and compared to that of cellulose fibers before treatment. This is also true for the effect of heat on cellulose fibers especially in the presence of oxygen due to the oxidation process. These results were compared with the results obtained for imported cellulose, which was showed that it contains high percent of water vapor, whereas the unbleached cellulose had the higher percent of volatile materials. This reflects the relation between the type of cellulose and it’s sources.