The present disclosure provides improved sensor assemblies for gases. More particularly, the present disclosure provides for gas sensor assemblies operating at high temperature. Improved high temperature sensor assemblies for reducing gas are provided. In some embodiments, the present disclosure provides advantageous impedancemetric high temperature gas sensor assemblies based on electrospun nanofibers and having selectivity towards reducing gas, and related methods of use. In exemplary embodiments, the present disclosure provides for impedancemetric high temperature gas sensor assemblies having selectivity towards reducing gas. In certain embodiments, the sensor assembly includes electrospun nanofibers. Impedancemetric techniques have been employed at high operating frequency (e.g., 10 5 Hz) for the first time to provide real-time assemblies, methods and devices to sensitively and/or selectively detect reducing gas (e.g., CO, C 3 H 8 (propane), etc.) at high temperatures (e.g., at about 800°C).