AbstractPolymerisation of methyl acrylate (MA) initiated by O2‐ascorbic acid (AA)‐Cu2+system was studied in aqueous medium at 40°C. The rate of polymerisationRp, was found to increase, remain constant, and then decrease with increasing [Cu2+].Rpwas found to depend on [Cu2+]0,6, [AA]0, [O2]0,6, and [MA]1,3in the increasing region, on [Cu2+]0, [AA]0, [O2]0,6, and [MA]1,6in the constant region and on [Cu2+]−0,9, [AA]0, [O2]0,7, and [MA]2,0in the decreasing region. Rate laws were derived assuming a plausible reaction mechanism for the different regions.Rpincreased with ionic strength and decreased with [H2SO4,]. An initial increase, then steady state followed by a decrease in rate with temperature was noticed in the range 25 − 55°C.kp/kt1/2values were calculated and compared with literature values. Chain lengths were determined viscom