A spectroscopic study of the Stark effect in the predissociating v þ ¼ 0 Rydberg states of nitric oxide, (n ¼ 13-16) is reported. The states are excited by two-colour excitation via the A 2 AE þ , v ¼ 0, N ¼ 0 state in the presence of a field in the range 0-1125 V cm À1 , and the excitation is observed by using (2 þ 1) REMPI detection of nitrogen ( 2 D) atoms formed by predissociation. The spectra recorded over a range of fields are compared with, and show excellent agreement with, multichannel quantum defect theory (MQDT) simulations of the absorption spectra applied in the bound state formalism of Sakimoto [J. Phys. B. 22, 2727[J. Phys. B. 22, (1989]. The spectroscopy demonstrates the possibility of producing N( 2 D) or O( 3 P) atoms with very narrow centre-of-mass frame speed distributions and arbitrarily selected speed.