Optical emission spectroscopy has been applied to study the OH radicals and O, H, and N active atoms produced by a high-voltage negative pulsed streamer corona discharge of N-2 and H2O mixture gas in a needle-plate reactor at one atmosphere. The relative vibrational populations and the vibrational temperature of N-2(C, v') were determined. The effects of pulsed peak voltage, pulsed repetition rate, and the addition of O-2 on the relative populations of OH(A(2)Sigma) radicals, O(3p(5)P), H-alpha (3P), and N(3p(4)P) active atoms were investigated. It was found that the relative populations of those radicals increase with increasing pulsed peak voltage and pulsed repetition rate. The relative population of OH(A(2)Sigma) radicals decreases with increasing O-2 flow rate, while the relative populations of O (3p(5)P), H-alpha (3P), and N (3p(4)P) active atoms exhibit a maximum over the studied range of the O-2 flow rate. The involved physicochemical processes have also been discussed.