It appears that the July issue of Dengeki Bunko Magazine is confirming that the third season of the anime adaptation of Kazuma Kamachi and illustrator Kiyotaka Haimura's
A Certain Magical Index ( Toaru Majutsu no Indekkusu) light novel series will premiere this October, during the Fall 2018 anime season.
The first 24 episode anime season premiered on October 2008 and a second season began airing on October 2010. It concluded in April 2011, meaning fans of the series will have waited seven long years for a continuation. Although, it should be noted that a spinoff manga series, titled A Certain Scientific Railgun, also received an anime adaptation that consisted of two season to date and aired in between seasons of Toaru Majutsu, filling the void.
Additionally, Hiroshi Nishikiori is confirmed to be directing the new season with Hiroyuki Yoshino adapting the script and character designs provided by Yuichi Tanaka.