Dissociative ionization of 1,4-bis(2,5-phenyloxazolyl)benzene (POPOP) molecule by electron impact in gaseous phase is studied. Potentials of appearance of some fragments of the molecule under study are determined from the experimentally measured dependences of ionization cross-section on the ionizing electron energy. A new ion with m/ z = 144 [C 9H 6ON] + is detected in the mass spectrum of the POPOP molecule, being complementary to the fragment with m/ z = 220 [C 15H 10ON] +. The threshold of appearance of this ion is determined ( E ap = 9.51 eV) as well as the first ionization potential of the POPOP molecule and fragment ion appearance potentials.