The same apparatus used for the study of CO₂ has now been used to study the products of ionization in NO₂ and N₂O. Thermal dissociation is so serious in NO₂ that the results are somewhat unsatisfactory but NO₂⁺, N⁺ and O₂⁺ are found as primary ions and their appearance potentials determined approximately. In N2O the results were more satisfactory and the apperance potentials 12.9, 16.3, 15.3, 21.4 were found for the primary ions N2O+, O+, NO+, N+ respectively. In both gases other primary ions were probably present but obscured by ions from products of thermal dissociation. As in CO4 the observed potentials agreed within the limits of error with calculated values.