Abstract: A process for producing an electrical resistor of a ceramic or glass-ceramic substrate with reentrant cavities or pores having directly adhered thereon a metallic foil, said foil substantially having the configuration of the adjoining surface of said substrate, comprises placing in direct contact a ceramic or glass-ceramic substrate with the required cavities or pores and a metallic foil of an electrically resistive material patterned to give a required electrical resistance value, maintaining the direct contact between the substrate and foil while subjecting the assembly to equal pressure from every side so as to adhere said foil to said substrate without any intervening bonding agent between the substrate and the foil, and securing electrically conductive terminals in electrical contact with spaced regions of said foil.