Photocrosslinking of low-density polyethylene, (LDPE), polypropylene (PP) and their blends was investigated using xanthone and triallyl cyanurate as a photoinitiator and a coagent, respectively. The influence of the change of UV-irradiation conditions on the yield of photoinitiated processes was found to be very similar at any composition, while the crosslinking efficiency decreases with increase of PP content in the blend. The mechanism of the TAC action in photocrosslinking process was proposed and the effect of TAC reactions is discussed with regards to the effectivity of crosslinking of LDPE, PP, or the blends.