Suction nucleate boiling (consisting of saturated pool boiling on a porous heat source with the generated vapor exhausting through the pores) was investigated experimentally and theoretically. The experimental results demonstrated that: (1) interfacial free energy can be used to direct the flow of liquid and vapor in a desired direction and to separate vapor from liquid at the point of vapor generation; (2) the heat transfer coefficient for suction nucleate boiling is higher than that associated with normal boiling; and (3) a porous heat exchanger can be designed to give stable transition from nucleate to film boiling. The theoretical analysis, which was based on experimental observations, indicated that extremely high heat fluxes and heat transfer coefficients are possible with small pores. Comparison of the experimental and theoretical results demonstrated that the full potential of suction nucleate boiling was not attained in the experiments and indicated some of the experimental refinements neededto attain this potential.