Presented are the results of experiments that investigated nucleate boiling of PF-5060 on microporous Cu surface layers at saturation and 10 K, 20 K, and 30 K subcooling. The three microporous layers, electrochemically deposited on 10×10mm2 Cu substrates and investigated herein, are ∼139 μm, 171 μm, and 220 μm thick. The critical heat flux increases linearly with increased subcooling, Δ Tsub, at an average rate of 4.5%/K. For the 171 μm thick, Cu microporous surface, saturation boiling CHF of 27.8 W/cm2 increases to 63.25 W/cm2 at Δ Tsub =30 K, while the saturation hMNB of 13.5 W/cm2 K decreases slightly to 12.7 W/cm2 K at Δ Tsub =30 K. The values of the surface superheat, Δ Tsat, at hMNB and CHF increase from 2.0 K and 2.16 K at saturation to 4.2 and 6.42 K at 30 K subcooling. © 2011 American Society of Mechanical Engineers.