Plasma-polymerized m-xylene (PPm-X) thin films have been prepared using a dry and flawless process. Films were smooth and of light-tea colour. UV-Vis spectroscopic investigations have been carried out on unannealed, annealed and aged PPm-X thin films to ascertain the effect of annealing temperature and aging on the optical properties of PPm-X. The bandgap, allowed direct transition energy gap and indirect transition energy gap have been determined. The results are discussed in the light of possible structural modification in PPm-X thin film on annealing and aging.