Mild hypothermia is a robust neuroprotective treatment for stroke. Understanding the mechanisms underlying hypothermia's benefits will lead to more effective treatments to prevent stroke damage. Delta protein kinase C (δPKC) is a kinase that has been strongly implicated in executing ischemic damage. We investigated the effects of hypothermia on δPKC activation, as determined by its subcellular translocation, proteolytic cleavage, and phosphorylation in a focal cerebral ischemia model. The amount of constitutively activated C-terminal catalytic fragment of δPKC (CF-δPKC) increased after stroke. Both hypothermia (30 C) and the caspase-3-specific inhibitor, Z-DQMD-FMK, blocked the accumulation of activated δPKC in the penumbra. Other hallmarks of δPKC activation, its translocation to the mitochondria, and nucleus were observed in the penumbra as early as 10 mins after reperfusion. These events were blocked by hypothermia. Hypothermia also blocked CF-δPKC increases in the mitochondria and nuclei. Conversely, a specific δPKC activator, ψδRACK, decreased the neuroprotective effect of hypothermia. Finally, δPKC activity may lead to mitochondrial injury and cytochrome c release, as the timing of cytochrome c release corresponded to the time course of δPKC translocation. Both cytochrome c release and δPKC translocation were blocked by hypothermia. In conclusion, hypothermia protects against ischemic damage in part by suppressing δPKC activation after stroke.