A man who triggered an explosion at the Australian Christian Lobby's headquarters will face trial for arson.

Jaden Duong, 36, is accused of lighting gas cylinders inside a van parked outside the building in Canberra, causing $10,000 worth of damage.

Duong suffered severe burns in the blast and maintains he was mentally unwell at the time.

Police documents reveal he hired the white van from Canberra airport using a US driving licence and purchased four gas bottles from service stations in the days before the explosion.

The documents suggest the decision to blow up the ACL building was 'spontaneous' and Duong's lawyers told the court his involvement in the incident was not disputed but his mental state at the time was significant.

Video footage after the incident showed a man in dark clothing, thought to be Duong, walking along a nearby street with his arms outstretched in front of him and Duong arrived at Canberra Hospital about an hour and a half after the blast with burns on his face and arms.

The ACL is a Canberra based group leading a fight against Australia's upcoming public vote on legalising gay marriage, which will be held through a postal ballot.

The poll will not be legally binding and the Australian parliament would still have to approve legislation to pass same-sex marriage.

But the ACL have campaigned hard against the change, warning of many 'hidden' consequences and claiming redefining marriage will threaten freedom of speech, take away religious freedom and remove children's rights to have a mum and dad.

Duong is due in court today for the first time and will be back later this month to stand trial.