Abstract: A method of increasing a thermal conductivity of a subterranean formation and a hydrocarbon-containing material comprises introducing nanoparticles having a high thermal conductivity into the subterranean formation. The nanoparticles adhere to surfaces of the hydrocarbon-containing material and increase the thermal conductivity of the hydrocarbon-containing material. A heating fluid is injected into the subterranean formation and contacts the nanoparticles. Heat is transferred to hydrocarbons of the hydrocarbon-containing material and reduces a viscosity of the hydrocarbons. Methods of transferring heat to a hydrocarbon-containing material, as well as methods of recovering hydrocarbons from a subterranean formation are also disclosed.