Use of a coincidence technique for registration of fragment ions and photoelectroms from dissociative ionization of molecules opens the possibility of studying the photoionization of oriented molecules in a gas phase. The first results obtained by this technique for O₂ molecules are presented. The angular distribution of photoelectrons as a function of an angle between molecular axis and a photoelectron momentum is measured for the B²Σ_g^- final ionic state using the HeI resonance radiation. From measured data it follows that the ratio of channel cross sections is σ_σ/σ_π=0.67±0.08.