The endothermic associative ionization reaction N(2 D) + O(3 P) → NO∗∗ → NO(1Σ+) +e- in slow collisions of the atoms has been considered in terms of the multichannel quantum defect theory. The dependences of the partial and total cross sections of the reaction on the energy of the colliding atoms in the range of 0-0.3 eV have been calculated. It has been shown that the cross sections have a pronounced resonance structure, which is formed as a result of the multichannel interaction of autoionization states of the intermediate Rydberg complex NO∗∗ with dissociative states. The temperature dependence of the reaction rate constant is presented. The results are compared with those of other calculations and available experimental data.