The ultraviolet photodescomposition of two of the main components of the sex pheromone of the insects, the Cydia pomonella and Lobesia botrana ((E,E) 8,10 dodecadien-1-ol and (E,Z) 7,9 dodecadienyl acetate) has been studied at room temperature and different conditions of acidity (pHs: 3,5,7,8 and 10) dissolved oxygen content (3 and 6 mg/L)According to the experimental results, the degradative process of (E,E) 8,10 dodecadien-1-ol and the (E,Z) 7,9 dodecadienyl acetate follows a first order kinetic. For the (E,E) 8,10 dodecadien-1-ol the degradation rate increases as the pH decreases, and, on the contrary, the degradation rate increases as the pH increases for ecreases the (E,Z) 7,9 dodecadienyl acetate. In both compounds, an increase in oxygen concentration favours the descomposition rate.