Compounds of selenium have been associated with potent antioxidant properties. Hence, the present study is aimed at comparing the antioxidant properties of two selenium compounds - diphenyl diselenide (DPDS) and selenium dioxide (SeO2). This was done by measuring their free radical scavenging ability, ferric reducing and Fe (II) chelating properties.Moreover their inhibitory effect against prooxidant - induced lipid peroxidation was also determined in the brain and liver homogenate of rat in a simulated hyperglycemia model in vitro. Their effect on lipid peroxidationwas further tested by pre-incubating and post incubating the selenium compounds with hepatic tissues in the presence of the prooxidants. Results showed that none of the two compounds scavenged DPPH radicals and chelate Fe (II).Meanwhile, when pre Â incubated, DPDS markedly reduced Fe3+, and demonstrated potent and concentration dependent inhibitory effect against lipid peroxidation regardless of the prooxidant causing oxidative assault. Furthermore, the potent inhibitory effect ofDPDS against lipid peroxidation was not altered in the presence of high glucose concentration but was lost on post incubation. On the other hand, selenium dioxide did not show any significant activity in all antioxidant parameters determined. From the foregoing, DPDS is a potent antioxidantwhile seleniumdioxide is not. This observation may explain why organic selenium compounds are better antioxidants than their inorganic counterparts. Hence, research efforts should be tailored towards the discovery and characterization of organic selenium compounds that could be exploited as panacea to free radical menace.