Photooxidative degradation of cis 1,4-polybutadiene in diluted benzene solution and benzene/hydrogen peroxide emulsion have been examinated using viscosimetry, GPC, FTIR, UV-Vis spectrometry and iodometric titration. Efficient photooxidation and photodegradation of PB in presence of hydrogen peroxide was observed. The acceleration effect of photoprocesses in PB is caused by hydroxy (HO.) and hydroperoxide (HOO.) radicals. The mechanism of PB reactions with free radicals proceeding from hydrogen peroxide and influence of benzene on photodegradation of PB have been discussed.