By Agence France-Presse
The state intends to adopt the new execution method as prison officials are unable to acquire the necessary drugs for lethal injections -- the method currently employed by all American states that carry out the death penalty.
States have struggled to obtain lethal injection drugs as manufacturers and suppliers increasingly have shunned them under pressure from death penalty opponents.
The plan would see Oklahoma resume executions for the first time in three years, after they were halted following a series of mishaps.
A grand jury investigating those errors, including the administering of the wrong drug during a 2015 lethal injection, recommended the use of nitrogen gas as an alternative, according to The Oklahoman newspaper. State lawmakers then passed a law approving the gas's use.
"Using an inert gas will be effective, simple to administer, easy to obtain and requires no complex medical procedures," Oklahoma Attorney General Mike Hunter said.
Nitrogen gas exposure is known to cause death within minutes, with those exposed experiencing fatigue, dizziness, loss of breath and euphoria before losing consciousness, Hunter's office said in a statement.
Oklahoma's prisons chief said the readily-available gas was a better option than trying to find new lethal, injectable drugs.
"Trying to find alternative compounds or someone with prescribing authority willing to provide us with the drugs is becoming exceedingly difficult, and we will not attempt to obtain the drugs illegally," Oklahoma Corrections Director Joe Allbaugh said.
Prison officials must still develop policies and procedures for how the gas would be administered.
Executions were not expected to resume until at least the end of the year, according to The Oklahoman.