An apparatus is provided for introduction and/or removal of a substrate into and/or from a process chamber of a vacuum coating unit that includes a process region adjoined by a lock chamber separable from surrounding atmosphere and from the process region by vacuum-tight lock gates. The process region encompasses a process chamber and a transfer chamber for altering transport speed. A vacuum-tight gate on the inlet side of a lock system is opened, the substrate is transported into the lock system and the gate is closed. Pressure in the lock system is subsequently matched to pressure in a subsequent space. An outlet-side gate of the lock system is opened and the substrate is transported from the lock system. The lock system includes a lock chamber and the adjoining transfer chamber. A passage between the transfer chamber and lock chamber remains open during introduction or removal of the substrate.