Indonesia resumed executions in 2013 after an unofficial four-year moratorium.
President Joko Widodo has said he will not grant clemency to anyone on death row who was convicted of drug offences.
The pair and seven other Australians then aged between 18 and 28 were arrested in Bali in April 2005 with more than 8.3kg of heroin.
Sukumaran and Chan were named as ringleaders of the group and sentenced to death in 2006.
Following various appeals, the other seven are now serving either life or 20 years in prison.
Previous executions have been carried out at night by firing squad in Indonesia. Condemned prisoners were shackled, taken to a remote floodlit clearing and strapped to a wooden cross. The prisoners were hooded to face 12 executioners armed with rifles who aimed at targets over their hearts.
"Executions are not clean killings," their Australian lawyer, Julian McMahon, told AAP.
"If the prisoner isn't dead straight away, the commanding officer is meant to walk up and then put a bullet in the head."