The intriguing properties of graphene has paved way for many potential biomedical applications like drug delivery, tissue engineered scaffold, bio sensing and so on. Here, we report the interaction of Maura reduced graphene oxide (MRGO) with the peripheral blood mononuclear cells (PBMNCs), as there is a likelihood of graphene coming in contact with the blood through intentional or accidental exposure. MRGO was synthesized by reducing graphene oxide using Halomonas Maura and autoclaved subsequently to prevent microbial contamination. It was characterized by TEM, AFM and FITR. Initial cytotoxicity was conducted in L929 cells to get the dose response. Oxidative stress potential, effect on proliferative capacity, genotoxicity and induction of apoptosis in PBMNCs treated with MRGO were assessed. MRGO elicited a dose dependent ROS generation which promoted apoptosis in PBMNCs. Proliferation of these cells were also found to be hindered. However, MRGO did not induce genotoxicity and generation of reactive nitrogen species. In conclusion MRGO shows a dose dependent toxicity in cells, generating ROS, inducing apoptosis and affecting proliferation, which may be due to the loss of exopolysaccharide coating due to autoclaving. This study raises a serious concern regarding the in vivo biomedical application of MRGO, where IV and IP are the main routes of exposure. Further evaluation is required regarding the interaction of autoclaved MRGO with the blood cells.