Experiment 022 was the 22nd genetic experiment created by Jumba with Hämsterviel's funding. He was designed to shoot donuts from his mouth that can restrain movements. 022 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai.
Hertz Donut is a green seahorse-like experiment with bright purple eyes, a donut-like mouth, six ears, and a long curling antenna winding behind his head.
Hertz Donut can confine and restrict movement by firing donuts at a target. He has the ability to speak fluently and hops instead of walks.
Hämsterviel gained possession of Hertz Donut under unknown circumstances and modified him to wreak havoc on his behalf. In the episode "Dorkifier", Hämsterviel intended to send Hertz Donut to capture Stitch, but accidentally sent the pod for Dorkifier instead. After realizing his mistake, Hämsterviel finally sends Hertz Donut after Yuna and Stitch. After wreaking havoc at a soccer match, Stitch is able to defeat him.
- Hertz Donut is one of the rare experiments to not have black eyes like most experiments, having bright purple eyes instead.
- Hertz Donut's pod color is red.