[en] Experimentally determined is the effect of the 14-MeV neutron pulse flux upon the electric strength of a transformer oil under a simultaneous action of pulse voltage with pulses about 1 microsecond long. The principle of action of the experimental installation is described and its structural block diagram is presented. The results that have been obtained make possible a conclusion that when the transformer oil is acted upon by 14-MeV neutrons at flux density of 10⁵ neutrons/cm² per 1 microsecond pulse the probability of a breakdown under the single action of neutron pulses and of a high voltage is higher by 10% as compared to that in the absence of the action of neutrons. When transformer opil is acted upon by neutron and high voltage pulses at 1 Hz frequency, the arithmetic mean of its breakdown voltage is by 7 % less than in the absence of the neutron pulse