Time-resolved absolute OH density measurements in a millisecond-pulsed DC glow discharge from carbon dioxide with water admixture by laser-induced fluorescence (LIF) spectroscopy are presented. For that purpose, a novel technique is suggested to calibrate the OH LIF setup by means of two-photon absorption LIF spectroscopy measurements on a CO-filled gas cell. OH densities in the order of 1018 m−3 are reported at a pressure of 6.67mbar with a water admixture of 20% and a discharge current of 50mA. Furthermore, the time evolution of the CO2 conversion is determined from collision energy transfer LIF and validated against literature. The time-dependent rotational temperature of OH is obtained with LIF thermometry.