First episode where they discover the factory.

Season 1

9.3

.

2003

.

26 Episodes

After discovering a parallel universe hidden inside a supercomputer, four students must stop a renegade virus from destroying the secret world.

Season 2

9.3

.

2005

.

26 Episodes

The Lyoko Warriors have their work cut out for them as XANA gains power, with an ability to possess humans and create even more mayhem on Earth.

Season 3

9.2

.

2006

.

13 Episodes

As Season 3 opens, XANA has escaped from the supercomputer and is bent on destroying Lyoko so that the Warriors will be unable to stop his evil plots.

Season 4

9.3

.

2007

.

30 Episodes

Jeremy and Aelita must rebuild a new Lyoko to replace the one XANA maliciously destroyed at the end of the third season.