This article reports the effect of three cobalt carboxylates-cobalt stearate (CoSt(3)), cobalt patmitate (CoPal(3)) and cobalt laurate (CoLau(3))-on the thermo-oxidative degradation of low-density polyethylene (LDPE) films prepared by sheeting process. The carboxylates were blended with LDPE in the concentration range of 0.05-0.2% (w/w). The degradation was monitored by techniques such as FTIR spectroscopy, change in the mechanical properties (tensile strength and elongation at break), viscometry, surface electron microscopy, melt flow index measurements, and apparent density measurements. Studies indicate that films containing these additives are highly susceptible to thermooxidative degradation. Oxygen containing functionalities such as carbonyl and vinyl species are generated on the surface of polyethylene because of thermo-oxidation, as indicated by FTIR studies. This oxidative process is accelerated in the presence of cobalt carboxylates. The degradation of LDPE was found to increase proportionally with concentration as well as with increasing chain length of the cobalt carboxylate, and follow the order CoSt(3) > CoPal(3) > CoLau(3). (c) 2006 Wiley Periodicals, Inc.