Artem Vasilyev, 27, of Findon, in Adelaide's western suburbs, had pleaded not guilty to one count of committing other acts done in preparation for, or planning, a terrorist act, between July 22, 2020 and September 28, 2021.
There was no visible reaction from Vasilyev when they jury foreperson delivered the verdict on Wednesday afternoon.
It came after nearly 13 hours of deliberations that began on Monday.
Vasilyev has pleaded guilty to 22 firearms offences stemming from two police raids on his home in 2021 and will remain in custody.
Justice Sandi McDonald ordered that he return to court on June 20 for a directions hearing on those charges.
During the trial, defence lawyer Scott Henchcliffe KC had told the jury the main reason Vasilyev was not guilty was that there was very little evidence suggesting he was interested in the Cherry Gardens substation, let alone that he intended to attack it.
"The fact that Mr Vasilyev never looked for Cherry Gardens substation in Google Maps or in his search browser is the elephant in the room," he said.
Prosecutor Justin Hannebery KC had told the court Vasilyev was an adherent to a political ideology that had the promotion of white nationalism as its goal, through force and terror.
Artem Vasilyev will remain in custody having pleaded guilty to 22 firearms offences. (HANDOUT/SUPREME COURT OF SOUTH AUSTRALIA)
Mr Henchcliffe said Vasilyev had a "very curious mind" and had obtained documents from all sorts of places.
"There was a substantial quantity of extreme and racist material and I don't in any way defend the ideology of that. He had some esoteric interest but that does not excuse the indefensible. But having that material doesn't make him guilty of this charge," he said.
In 2021, police twice raided the home the former Department of Defence employee and electronics engineer shared with his mother, seizing an improvised AR-15 semi-automatic firearm produced by a 3D printer.
A 3D printer was also found, along with a printout containing the methodology to manufacture 3D FGC firearms.
Hard drives on the PC contained documents on firearms, explosives, how to avoid or escape detection, and nationalist and racist ideology, the court was told.
Images and video files related to anti-semitic, neo-nazi and right-wing extremism were also located.
"The fact that we've been here more than three weeks and we've really only had time to show you a tiny portion of this material reveals to you that Mr Vasliyev was relentless and obsessive in compiling this volume of material," Mr Hannebery said during the trial.
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