Electrical resistivity measurements of polycrystalline iron have been performed at 5, 7, and 15 GPa and in the temperature range 293–2200 K by employing a four-wired method. The kinks in electrical resistivity associated with solid iron phase transitions and the solid to liquid transition were clearly observed upon increasing temperature. Geometry corrections due to volume variations with pressure and temperature were applied to the entire data set. High pressure and temperature thermal conductivity were calculated by fitting resistivity data through the Wiedemann-Franz law. The temperature dependences of electrical resistivity and thermal conductivity for α, γ, and ε solid iron have been determined at high-pressure conditions. Our study provides the first experimental constraint on the heat flux conducted at Mercury's outmost core, estimated to be 0.29–0.36 TW, assuming an adiabatic core. Extrapolations of our data to Martian outer core conditions yield a series of heat transport parameters (e.g., electrical resistivity, thermal conductivity, and heat flux), which are in reasonable comparison with various geophysical estimates.