Oklahoma Attorney General Mike Hunter said in a statement that the state would use the gas as its primary means of execution once a procedure for its use had been finalised.
A spokeswoman for Hunter declined to comment on when executions might resume following a three-year hiatus. It was not likely until the end of the year at the earliest, The Oklahoman newspaper reported.
Oklahoma has not carried out an execution since 2015 after a series of mishaps, including a botched lethal injection where an inmate was seen by witnesses writhing in pain on a death chamber gurney.
Oklahoma is turning to nitrogen after it, and other states, have been unable to acquire drugs required for lethal…