Abstract: Neutral electrolytes, relatively neutral electrolytes, metal oxides, metal hydroxides and/or organic exothermic hydration chemicals may be hydrated with water at a controlled location in a subterranean formation to generate sufficient exothermic heat to at least soften and possibly melt and flow bitumen at or near the location. This controlled and localized heating would be useful in drilling through relatively thick bitumen or “tar” beds. In one non-limiting embodiment the exothermic hydration reaction does not generate appreciable amounts of gas. Alternatively, the exothermic reaction may be used to liberate hydrocarbons from gas hydrates in an embodiment where the evolution of gas is acceptable.