According to the provisional charge sheet, the two had, during the period of October 2015 and and 8 July 2016, conspired to commit terrorist activities in Johannesburg.
The State said the brothers "unlawfully and intentionally conspired to commit the crime of terrorism", planning to cause explosions at a Mission of the United States of America and Jewish institutions located with South Africa.
"All in order to cause to endanger life, cause death and serious bodily harm and the destruction or substantial damage to such institutions, and in the pursuance of such conspiracy incite or spread feelings of terror in the civilian population of South Africa and in particular the US and the Jewish sector thereof and to intimidate the government of the United States of America."
The conspiracy and incitement were linked the "political, religious or ideological motives" of the ISIL, read the charges.
The second charge was linked to the alleged plan by the brothers to leave for Syria and join ISIL, "to engage in terrorist activity by conspiring to leave South Africa in order to join ISIL in Syria".
The brothers were also charged with contravening the constitutional democracy of the country by attempting to commit acts associated with terrorist activities.
The case against suspects, Brandon-Lee Thulsie and Tony-Lee Thulsie, was postponed to the 19th of this month.