Optical emission spectroscopic studies were conducted on atmospheric pressure electrodeless microwave plasmas generated in 95% carbon dioxide-5% hydrogen mixture. The plasma power was fixed at 2kW and the mixture gas flow rate was varied from 5 to 20 slpm. Optical emission spectroscopy was measured at center of plasma reactor. The rotational and vibrational temperatures of the plasma were measured at the C2 Swan band wavelength in the ranges of 500-517nm and 548-565 nm. The electron number density of the plasma was calculated by measuring Stark broadening of hydrogen Balmer-beta line shape at 486.13nm. Between the rotational and vibrational temperatures had little difference and the temperature was measured around at 6,200K. The electron number density of the plasma was calculated to be approximately 2.55× 10^14 cm^-3. Thermodynamic-equilibrium calculations indicated that the temperature corresponding to the measured electron number density of the plasma was 6,285K, that is similar to the temperatures measured according to the C2 Swan band spectra. Therefore, there was no difference between the electron and gas temperature and the plasma was in local thermal equilibrium (LTE).