The biggest consumers of water are textiles, tannery, electroplating and pulp and paper industries and these are also the most serious polluters of environment. Photocatalytic degradation has been considered to be an efficient process for de-radation of organic pollutants, which are present in the effluents released by these industries. The photocatalytic bleaching was carried out on cationic dyes (methylene blue, crystal violet, malachite green) in the presence of semiconducting iron(III) oxide and was observed spectrophotometrically. The effect of various operating variables like pH, concentration of dyes, amount of semiconductor, light intensity, particle size, stirring, etc. was also observed oil the efficiency of the reaction. A tentative mechanism has also been proposed for this photocatalytic bleaching.