In this paper, nanofluids containing xGnPs and xGnPs oxide were prepared due to superb thermal properties and low cost. Pool boiling experiments were performed for different particle concentrations. The critical heat flux (CHF) of nanofluids when boiled over a NiCr wire increased with increasing concentrations of xGnP and xGnP oxide particles in the base fluid. We determined that the xGnP oxide nanofluids with 0.005 vol% dispersed particle concentration had the most enhanced CHF. Although the largest CHF enhancement was observed for the nanofluid with 0.005 vol% xGnP oxide, no reduction was observed in the contact angle.