In organic chemistry, many metals have been utilized to form radicals. For example, the first radial detected, the triphenylmethyl radical, was synthesized by abstracting chloride (Cl • ) from triphenylmethyl chloride [(C6H5)3CCl] using silver (Ag) metal. We propose that CO2 on the Cu metal surface can undergo a radical reaction. Here, the Cu • , with a single unpaired electron, interacts with CO2 to yield a carbon-centred radical (O=C • -O-Cu). If we assume that the formation of the radical (O=C • -O-Cu) is the first step for the electrochemical CO2 reduction, we can obtain an insightful explanation for the formation of a wide range of products.