A solid-state sensor has been designed that uses an ion conducting membrane to perform conductivity and corrosion measurements in natural gas pipelines up to 1000 psi (6.9 MPa). Changing gas composition between nitrogen, methane, and a methane/carbon dioxide blend was found to have little impact on the membrane conductivity. Corrosion monitoring was also performed using linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) for X-65 carbon steel in gas at 60 °C for dew points between 1 and 18 °C. Corrosion rates ranged between 0.01 and 0.1 μm yr-1 and increased with increasing dew point. Corrosion rates were found to depend strongly on the water content or relative humidity but were largely independent of total pressure. Addition of 5 % vol. carbon dioxide was found to slightly increase the measured corrosion rate.