The present work reports for the first time a novel method for poly (acrylic acid)-coated nanoceria (PAA-CNPs) quantification based on its oxidative activity towards the Fe(CN)(6)(3-/4-) red-ox system. Stable suspensions of 3 nm-sized PAA-CNPs were first prepared and characterized. It was found that the presence of PAA-CNPs on the electrode surface exerts a high oxidative effect on Fe(CN)(6)(4-) before the voltammetric reduction, being that effect evident in acidic and neutral pH. Such behaviour allows the rapid and sensitive PAA-CNPs quantification taking advantage of the chronoamperometric mode. By applying a voltage of 0 V, the value of the current recorded at 10 s is proportional to the amount of PAA-CNPs deposited on screen printed carbon electrodes (SPCEs). Under the optimized conditions, a detection limit as low as 3.15 x 10(13) NPs/mL with a linear dynamic range between 3.71 x 10(13) and 1.85 x 10(15) NPs/mL and a reproducibility (RSD) of 4% is obtained. To the best of our knowledge, this is the first time that such property of PAA-CNPs is studied and applied for quantification purposes. Furthermore, the proposed detection method does not require the chemical agents used in most existing assays for the detection of NP tags. We envisage that this methodology could open the way to further use of PAA-CNPs tags in biosensing as advantageous alternative to enzymes.