The present work was aimed that in vitro antioxidant activity of some novel synthetic mononuclear Ruthenium
(II) compounds namely, Ru (1, 10-phenanthroline)2(2-nitro Phenyl thiosemicarbazone)Cl2 (compound R1) and Ru (1, 10-
phenanthroline)2(2-hydroxy-phenyl thiosemicarbazone)Cl2 (compound R2) using [2, 29-azinobis-(3-ethylbenzothiazoline-
6-sulfonic acid)] (ABTS), Ferric reducing antioxidant power (FRAP), N, N-dimethyl-p-phenylenediamine (DMPD), 1, 1-
diphenyl-2-picryl hydrazine (DPPH) and Nitro blue tetrazolium (NBT) assays. The results concluded that both the
compounds (R1&R2) exhibited a significant antioxidant activity. But compared to reference standards, R1 was found to be
better free radical scavenging activity than R2.