New sensors and methods for qualitative and quantitative analysis of multiple gaseous substances simultaneously with both high selectivity and high sensitivity are provided. The new sensors rely on a characteristic difference in energy between the interaction of a particular substance with a catalyst coated heat transfer device (HTD) and a non-catalyst coated (or one coated with a different catalyst) reference HTD. Molecular detection is achieved by an exothermic or endothermic chemical or physical reaction between the catalytic surface of the sensor and the molecule, tending to induce a temperature change of the sensor. Both high temperature and non-destructive low temperature detection are possible. The magnitude and rate of endothermic or exothermic heat transfer from a specific molecule-catalyst interaction is related to molecular concentration.