It will premeire in 2019
During the event “Dengeki Bunko 25th Anniversary Fall Dengeki Festival” it has been revealed that the manga of “A Certain Scientific Accelerator” is getting an Anime adaptation that will premier next year. In the event they even revealed a teaser which you can see bellow:
Details about the staff are stil a mystery, although the voices of Accelerator and Last Order will be represented by Nobuhiko Okamoto and Rina Hidaka respectively.
Via: Anime News Network