We report a new type of step-growth radical addition-coupling polymerization (RACP) involving consecutive addition of carbon-centered radical derived from alpha,alpha'-dibromo dibasic ester to N=O double bond of C-nitroso compound followed by cross-coupling of carbon-centered radical and in situ formed nitroxyl radical, which produces alternating copolymers with high molecular weight and unimodal molecular weight distribution from saturated and unsaturated monomers.