The court considered it as proven that he had went to a terror training camp on the Turkish-Syrian border last summer.
There the defendant joined the radical islamic Al Nusra Front and had got "at least an ideological education and basic weapons training", judge Norbert Gerstberger elaborated in the grounds for the judgement.
Although the whole trial was based on circumstantial evidence, the offense of taking part in a terror camp was sufficiently proven against him, the judge announced.
The court orders are not final and will be reviewed in an instance of appeal as the defendant's lawyer pursued a nullity appeal against the verdict.
The Al Nusra Front is considered to be close to Al Queda, and is listed as a terrorist organisation by the UN Security Council.
The man accused of murdering four people in the Jewish museum in Brussels on May 24, Mehdi Nemmouche, is also thought to be a member of Al Nusra.