  Atmospheric pressure steam/oxygen plasma is generated by a 88 Hz, 6kV AC
power supply. The properties of the produced plasma are investigated by optical
emission spectroscopy (OES). The relative intensity, rotational, vibrational,
excitation temperatures and electron density are studied as function of applied
voltage, electrode spacing and oxygen flow rate. The rotational and vibrational
temperatures are determined simulating the bands with the aid of LIFBASE
simulation software. The excitation temperature is obtained from the CuI
transition taking non-thermal equilibrium condition into account employing
intensity ratio method. The electron density is approximated from the
H_{\alpha} Stark broadening using the Voigt profile fitting method. It is
observed that the rotational and vibrational temperatures are decreased with
increasing electrode spacing and O2 flow rate, but increased with the applied
voltage. The excitation temperature is found to increase with increasing
applied voltage and O2 flow rate, but decrease with electrode spacing. The
electron density is increased with increasing applied voltage while it seems to
downward trend with increasing electrode spacing and O2 flow rate.
