When performing an Accel Synchro Summon, the required Synchro Material Monsters must be themselves Synchro Monsters. As usual, 1 Tuner Monster and 1 or more non-Tuner monsters are required; this effectively makes the requirement 1 Tuner Synchro Monster and 1 or more non-Tuner Synchro Monsters.
In the anime, an Accel Synchro Summon can only be successfully performed when the user is in a state of Clear Mind. Accel Synchro Summoning can be performed even during the opponent's turn. When such a Summon is performed in the anime, the user and the Synchro Materials are shown to rapidly accelerate, briefly vanish, and then reappear behind their opponent along with their new Accel Synchro Monster.