The Fe2+/modified silica catalysts have been substituted with four types of transition metals such as Fe3+, Cr3+, Mn3+ and Mo. The catalytic activity of these catalysts has been tested for the oxidative degradation of Reactive Black 5 (RB5) at 30°C and pH 4.5. The substituted Fe2+/modified silica with Fe3+ (Fe2+:Fe3+/ m-SiO2) exhibited the highest catalytic performance compared to others transition metals by degrading the RB5 nearly to 95%. This catalyst possessed on high stability by maintaining its performance during the three successive cycles of reaction. These findings can be ascribed to the plausible enhancement in the formation of hydroxyl radicals (HO●) due to the effective redox between Fe2+ and Fe3+