There is a growing field of research into the physicochemical properties of metal oxide nanoparticles (NPs) and their potential use against tumor formation, development and progression. Coated NPs with biocompatible surfactants can be incorporated into the natural metabolic pathway of the body and specifically favor delivery to the targeted cancerous cells versus normal cells. Polyethylene glycol (PEG) is an FDA approved, biocompatible synthetic polymer and PEGylated NPs are regarded as "stealth" nanoparticles, which are not recognized by the immune system. Herein, PEGylated cupric oxide nanoparticles (CuO NPs) with either PEG 1000 or PEG 8000 were hydrothermally prepared upon properly adjusting the reaction conditions. Depending on the reaction time CuO NPs in the range of core sizes 11-20nm were formed, while hydrodynamic sizes substantially varied (330-1120nm) with improved colloidal stability in PBS. The anticancer activity of the NPs was evaluated on human cervical carcinoma HeLa cells by using human immortalized embryonic kidney 293 FT cells as a control. Viability assays (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT) revealed that CuO NPs could selectively reduce viability of tumor cells (IC values 11.91-25.78μg/mL). Reactive oxygen species (ROS) production, cell membrane damage and apoptotic DNA laddering were also evident by nitroblue tetrazolium (NBT) reduction, lactate dehydrogenase (LDH) release assays and DNA electrophoresis, respectively. CuO NPs strongly inhibited lipoxygenase (LOX) enzymatic activity with IC values 4-5.9μg/mL, highlighting in that manner their anti-inflammatory activity.