热失控（thermal runaway，又译：热跑脱）所指的情况是，当温度增高时引发的变化使温度更进一步的增高，产生恶性循环，因而导致某一种破坏性的结果。这是一种正回馈。

在化学工程，热失控是放热反应失去控制的情况，经常会造成爆炸。

当反应速率是温度增加的增量时，便会发生热失控，不仅导致温度进一步的增加，而且反应速率也会进一步的增加。放热的副作用和燃烧使温度变得更高，加速了热失控。热失控引起的化工事故，以1984年发生在印度波帕尔的1984爆炸最为著名，它是联合碳化物设在当地生产异氰酸甲酯的工厂。热失控也是炼油厂在加氢裂解过程中要注意的事。

Thermal runaway refers to a situation where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result. It is a kind of uncontrolled positive feedback.

In other words, "thermal runaway" describes a process which is accelerated by increased temperature, in turn releasing energy that further increases temperature. In chemistry (and chemical engineering), this risk is associated with strongly exothermic reactions that are accelerated by temperature rise. In electrical engineering, thermal runaway is typically associated with increased current flow and power dissipation, although exothermic chemical reactions can be of concern here too. Thermal runaway can occur in civil engineering, notably when the heat released by large amounts of curing concrete is not controlled. In astrophysics, runaway nuclear fusion reactions in stars can lead to nova and several types of supernova explosions, and also occur as a less dramatic event in the normal evolution of solar mass stars, the "helium flash".