Reciprocating heat pipes are novel heat pipes that are being developed for engine piston applications. These heat pipes have a high effective thermal conductance due to the impinging effects of liquid particles in the heat pipe. In this investigation, semiempirical correlations for the dimensionless temperature distribution and effective thermal conductivity of heat pipes are derived. Extensive experiments are conducted to investigate the effects of thermal and geometrical conditions on the performance of reciprocating heat pipes, and a large number of experimental data are generated. Experimental results indicate that the effective thermal conductance of the reciprocating heat pipe can be more than 300 times that of a solid copper bar of equal size. Comparison of the experimental data and correlation shows that the experimental data can be correlated to within ±30% by the correlation derived, which provides a quantitative relation for heat pipe design purposes.