The ability of hydrogenated detonation nanodiamond particles to participate in CO2 reduction reactions producing formate and acetate ions on their surface was demonstrated. The reactions proceed in air and CO2 under normal conditions and do not require light, thermal and electrochemical activation. The products of CO2 reduction reactions were analyzed using IR spectroscopy and mass spectrometry. Deuterated acetate ions were synthesized by reducing CO2 in heavy water vapor to confirm the reaction mechanism. Formation of multi-carbon compounds implies a low energy threshold of CO2 reduction on the surface of hydrogenated detonation nanodiamond. This makes the hydrogenated detonation nanodiamond a promising catalyst for efficient production of multi-carbon compounds by CO2 reduction.