The photochemical degradation of unpigmented and unstabilised polypropylene films can be monitored colorimetrically following reaction of the carbonyl groups produced, with 2.4- dinitrophenylhydrazine under acidic conditions. The highly colored 2,4-dinitrophenylhydrazone produced in the UV visible spectrophotometry at 340 nm. The degradative progress could also be seen fairly easily be examination of the irradiated polypropylene films under a scanning electron microscope.