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 NO+2, N+ and O+2 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.