The victim is in a "serious but stable" condition in the Royal Victoria Hospital, Belfast after being struck by a lit petrol bomb which was thrown into his Waterside home on Friday night.
Two youths smashed a living room window of the property at Ben Varden Avenue at 11.10pm and threw the missile inside.
It struck the man, setting him alight. The victim was rescued by neighbours, who managed to get him out of the house.
"I just can't get the images out of my head. It's shocking," one of the neighbours said.
"I tried to get in two or three times, but the smoke was too thick," he explained.
When he eventually got through the smoke, the neighbour said that the victim was lying on the living room floor on fire. The sofa was also alight.
Emergency crews initially thought his injuries were life threatening. After undergoing surgery twice, the victim remains seriously ill.
Chief Inspector Jon Burrows, Foyle Area Commander, told UTV: "We must stress the significant injuries to the victim - he was has been left with 35% burns.
"We're treating this as attempted murder. The people who did this are dangerous people. They're a danger to the community and we need to get justice for the victim."
Commander Burrows added that there is "no clear motive" for the attack.
"We have no indication yet as to what the motive is.
"This was an entirely innocent man, who was sitting on his sofa on a Friday evening minding his own business and he has been attacked in his own home by two people who have very nearly killed him.
"He is still extremely seriously ill in hospital. "
The male youths were described as being dressed in grey hooded tops with scarves over their faces.
It is believed they made off in the direction of Dervock Place.
"We really need the public's help in identifying these people and taking them off the streets," Commander Burrows added.
Derry SDLP councillor Gerry Diver has strongly condemned the attack, describing it as mindless.
A local resident, Councillor Diver said that he was on the scene within minutes.
"This is a shocking incident and our thoughts are with the man injured in this attack," he said.
"I am completely disgusted that such attacks are still going on in the city and my sympathies are with the victim. We pray that he makes a full recovery from his injuries."
He said the fire could have easily spread to adjacent properties on the avenue, which is a row of terraced houses.
"Petrol bombs are lethal weapons. If it hadn't been for the swift actions of this gentleman's neighbours, we could have dealing with a tragedy today.
"I urge anyone who may have any information relating to this incident to come forward to local PSNI without delay."