We investigate atmospheric pressure microwave (MW) plasma conversion in CO2 and CH4 mixtures (ie, dry reforming of methane, DRM). Promising energy costs of~ 2.8-3.0 eV/molecule or~ 11.1-11.9 kJ/L are amongst the best performance to date considering the current state-of-the-art for plasma-based DRM for all types of plasma. The conversion is in the range of~ 46-49% and~ 55-67% for CO2 and CH4, respectively, producing primarily syngas (ie, H2 and CO) with H2/CO ratios of~ 0.6-1 at CH4 fractions ranging from 30 to 45%. Carbon particles visibly impact the plasma at higher CH4 fractions (> 30%), where they become heated and incandescent. Particle luminosity increases with increasing CH4 fractions, with the plasma becoming unstable near a 1: 1 mixture (ie,> 45% CH4). Electron microscopy of the carbon material reveals an agglomerated morphology of pure carbon nanoparticles. The mean particle size is determined as~ 20 nm, free of any metal contamination, consistent with the electrode-less MW design.