AbstractFast neutrons deposit energy in chemical systems by means of elastic scattering, inelastic scattering, and various charged particle reactions. For the particular case of 14.6 Mev neutrons and 1:1 solutions of liquid N2and O2,the proportions by which the three classes of reactions contribute are, respectively, about 1:1:4. The initial linear energy transfer (ILET) in the same system is of the order of 20 ev/Å.Dosimetry in fast neutron radiation chemistry experiments may combine a quantitative consideration of each nuclear reaction with a measurement of the neutron flux. This method of dosimetry has been applied to experiments on the production of NO2in 1:1 liquid N2and O2with the result thatGNO2,the number of NO2molecules formed per 100 ev deposited in the sample, was found equal to 0.5±0.1. This result is surprisingly close to that observed for irradiations by Co50gamma rays and by electrons whose ILET is three orders of magnitude less than that for 14.6 Mev neutrons.