Quenching experiments with copper spheres were performed to characterize the transient pool boiling of aqueous nanofluids in the presence of graphene oxide nanosheets (GONs) at various dilute concentrations (<= 0.001 wt.%). The CHF enhancement was found to vary non-monotonously with increasing the concentration of GONs. This non-monotonic variation was in accordance with the surface wettability change due to the deposited GONs after quenching. In addition to the primary effect of the deposition layers, the non-negligible influence of the suspended GONs was also identified, especially at relatively higher concentrations. (C) 2014 Elsevier Ltd. All rights reserved.