This contribution reports on the synthesis and the main physical properties of CeO2 nanoparticles (which can be as small as 〈ϕCeO2〉 ∼ 3.9 nm in diameter) engineered for the first time by a completely green process using Hibiscus Sabdariffa natural extract as an effective chelating agent. Their morphological, structural and optical properties were investigated using various complementary surface/interface characterization techniques. Display omitted •1st time report on synthesis of CeO2 nanoparticles by a green process via Hibiscus Sabdariffa flower extract.•Hibiscus Sabdariffa's natural extract was used as an effective reduction/oxidizing agent.•Pure CeO2 nanoparticles were confirmed via HRTEM, XRD, ATR-FTIR, Raman, and XPS.