Abu Malik was described as a 'mid-level operator' for the terrorist group which has been persecuting tens of thousands of Christians as it advances over Iraq and Syria.
The group is attempting to set up an Islamic caliphate and has given Christians a warning to pay a tax, flee or die.
US Central Command said the militant was killed near Mosul on January 24.
He had worked at Saddam Hussein's Muthana chemical weapons plant before joining al Qaida in Iraq in 2005.
Since joining IS he has brought chemical weapons expertise to the terror group.
America said his death could "temporarily degrade" Islamic State.
The US-led coalition has conducted almost 2 thousand strikes against IS targets in Iraq and Syria since they began last September.