Linear and differential thin film thermocouples, typically 500-1000angstrom thick, were fabricated on flexible polymer and paper substrates by thermal evaporation. Both types of thermocouples had thermal sensitivities of approximately 4 muV/degrees-C, for temperatures between 20-degrees-C and 40-degrees-C, on the paper and polymer-coated paper substrates. The transverse thermal conductivity (k(t)), i.e., thermal conductivity in the direction perpendicular to the plane of the films, of polyimide (Kapton-H(R)) films, of a clay-coated paper, and of a polystyrene coating on paper were determined by depositing linear thermocouples on both sides of the films and raising the temperature of one junction and measuring the heat flux and, at equilibrium, the temperature of the other junction. Shear and Young＇s moduli of the polymer films were estimated from the measured thermal conductivity values, assuming the Debye model of thermal conductivity.