Barbiturate coma therapy (BCT) is a choice treatment for refractory intracranial hypertension after all surgical or medical managements have failed to control the intracranial pressure (ICP). It helps to reduce cerebral blood flow, cerebral metabolic rate of oxygen consumption and ICP. However, this therapy can also cause many complications. One of the underreported, but life-threatening complications is refractory hypokalemia, which can lead to subsequent rebound hyperkalemia after sudden cessation. We report our experience of managing unusual complication of refractory hypokalemia during BCT with thiopentone in postdecompressive craniectomy patient.