Electrochemically reduced graphene oxide (ERGO) films find growing interest as voltammetric sensors for trace detection of electroactive analytes due to their easy preparation and unique electrochemical properties. Here, we demonstrate that the reduction extent of the ERGO film, is a crucial determinant of the concentration detection limits of such ERGO-based voltammetric sensors. To show this, we prepared a series of ERGO films with various reduction extents through electro-reduction at different reduction potentials, examined their background currents and electrocatalytic activities by using dopamine (DA) as a model analyte. Results showed that the background current response on the ERGO modified electrode monotonically increased with increasing reduction extent of the ERGO film, whereas the highest electrocatalytic activity towards the oxidation of DA was observed on the partially electrochemically reduced graphene oxide (pERGO) film. Because of its relatively low background current and high electrocatalytic activity, the pERGO modified electrode exhibited the lowest concentration detection limit for DA and a simple voltammetric sensing platform for trace detection of DA has been developed. These results highlight the important role of the reduction extent of ERGO film in determining the detection limits of ERGO film modified electrodes as voltammetric sensors. We believe that our findings could be also of value in the further developing ERGO-based sensors for trace voltammetric detection of other electroactive analytes. (C) 2014 Elsevier Ltd. All rights reserved.