Synthetic Energon, colloquially referred to as Synth-En, is a form of Energon that can be created rather than having to be mined like normal Energon. The formula for Synthetic Energon was created by ancient Autobots and was placed in a Cybertronian Data Cylinder. It appears as a glowing green liquid.
The Synthetic Energon was created by Ratchet after he obtained a partial formula from Bulkhead, who had in turn absorbed the formula from a Cybertronian Data Cylinder. The data was released from Bulkhead's mind before the formula was complete, so Ratchet had to work out the remaining formula.
When Ratchet eventually did complete the formula, he began to create the Energon. He first tested it on a simple motor, but with the Autobot's Energon supply at a critical low and Ratchet desperate to help his friends, he decided to test the Synthetic Energon on himself. The Energon did enhance his strength, speed, and agility, but unfortunately because he didn't have the full formula, the energon was not created properly and caused a change in his personality that led to him to act aggressively and made his judgement irrational. After this incident, Ratchet elected to continue testing on machines, not Autobots. But little did they know that Knock Out discovered a drop of Synth-En in the energon mine where Ratchet engaged Megatron.
Knock Out later began experimenting with Synth-En to determine its potential as an alternate energy source, using C.Y.L.A.S., the fusion of the human Silas, and the remains of Breakdown, as a guinea pig. Infusing C.Y.L.A.S. with synth-en caused his human side to go mad with rage while burning out his natural energon reserves. Starscream saw potential in C.Y.L.A.S. as a supersoldier and devised a plan to mix a drop or two of Dark Energon in his next infusion to grant Megatron control over him through the Dark Energon shard in his body... with disastrous consequences. Not only did the synth-en corrupt Megatron's link to the trace of dark energon in C.Y.L.A.S., he also became an Energon-sucking Terrorcon that drained victims though a proboscis-like tongue and began rampaging through the Nemesis, infecting many of the Vehicon foot soldiers. He also incidentally freed Airachnid, allowing her to retake control of the Insecticon hive. Needless to say, Megatron was... less than pleased by the duo's actions once the situation was dealt with.
Knock Out later shipped entire crates of Synth-En to Shockwave's offsite laboratory where his Predacon clones were in development. However, when Predaking demonstrated sentience and Megatron feared he would lead the Predacons into eradicating the Decepticons, he chose to expose the project to the Autobots so they would destroy it. Wheeljack succeeded by detonating a grenade near the crates of synth-en, destroying the lab. Shockwave later investigated the aftermath, discovering that the synth-en had catalytic properties, transforming the Cybernucleic acid (CNA) in the clones into Cyber matter.
Following this discovery, the Decepticons began work on reconstructing the Omega Lock in order to restore Cybertron and cyberform Earth. During construction, Shockwave discovered the Synthetic Energon formula was incomplete and would need to be finished for the Omega Lock to function properly. Megatron directed Soundwave, who had been previously captured by the Autobots, to abduct Ratchet and bring him to the Nemesis. After much convincing, Ratchet agreed to complete his work on the Synth-En. Upon completion, Ratchet sent out a distress call during Predaking's rampage, and the Autobots began their assault on the Decepticon ship. With the Decepticons defeated and the ship seized, the Autobots returned to Cybertron and used the Omega Lock to reactivate the Core and bring their homeworld to life once more.
- When it is used on a Transformer, it changes their usual eye color to a glowing green color.
- As energon could be seen as a food analog for Transformers, this substance (due to its strength granting properties and its side effects) could be seen as an analog to a steroid.
- Ratchet displayed social negativity towards the other Autobots, especially Bulkhead after being injected by the synthetic Energon. Here were his actions:
- Bulkhead: used him as practice by throwing him against a wall, then throwing him at Optimus Prime when Ratchet was ordered to return to base.
- Bumblebee: calls him a wimp.
- Arcee: brought back the memory of Cliffjumper and stated disrespect for his death. (He also hits on her back at base)
- Optimus Prime: claims that he wastes time stopping Megatron's minor plots rather than trying to defeat Megatron once and for all.