Three commercial profenofos emulsifiable concentrate (EC) formulations 720 g/l (72% w/v) currently applied in Egypt from three different companies were studied for the effect of sunlight exposure and storage on the stability of profenofos and its relevant impurity 4-bromo-2-chlorophenol content. Exposure to sunlight and storage for more than 14 days at 54 ±2 ^oC indicated various degradation effects on profenofos content and increase the formation of its impurity 4-bromo-2-chlorophenol. Identification of profenofos content and degradation products were determined using GC–FID and GC-MS. From the obtained results the storage of profenofos at 54 ±2 ^oC at intervals 28, 42, 56 and 70 days showed serious effects on the degradation rate of profenofos and increase the rate of formation of 4-bromo-2-chlorophenol compared to exposure to sunlight for all profenofos formulations under study. The results showed variable rate of degradation of profenofos and the amount of its relevant impurity 4-bromo-2-chlorophenol for all samples sources under investigation. Analysis after storage using GC-MS identified three degradation products: 4-bromo-2-chlorophenol, O-ethyl-O-(2-chloro-4-bromo-phenyl)-phosphate and O-(4-bromophenyl) O-ethyl S-propyl phosphorothioate.