The COO-series cook droid, alternatively referred to as simply a COO cook droid, belonged to the class three droid category.
Back in 22 BBY, a culinary droid provided its services on the AA-9 Freighter-Liner called the Jendirian Valley. This vessel was transporting Senator Padmé Amidala along with her protector, the Jedi Anakin Skywalker, to Amidala's homeworld planet known as Naboo.
A COO-series cook droid was in service to the Alliance to Restore the Republic while aboard the starship Silver Arrow. Like other droids on the ship, the cook droid was infected by the Scourge. The Scourge then used the droids to murder all organic crew members. Later, the Scourge utilized the COO-series droid and other infected droids aboard the Silver Arrow to set up an ambush for Magna Tolvan's crew.
In 4 ABY, one unit was employed within Jabba's Palace. By 9 ABY, a unit was still stationed at the palace. When the former bounty hunter Boba Fett and Master Assassin Fennec Shand gained entry to the palace through a kitchen grate, the COO-series cook droid was in the process of preparing food alongside an EV-series sous-chef droid. The two droids detected the sound coming from the grate, which the EV-series believed was a rat. The cook droid instructed the sous-chef droid to locate the rat, and to contact the LEP-series rat catcher, but the EV droid was instead struck down by Fett. Stepping out from behind the counter to face Fett, the chef droid began to rotate the knives attached to its six arms. However, before the droid could launch an attack, Shand approached it from behind, severing its head.
A COO-series droid was obtained by the Plazir-15's government and repurposed for civilian tasks, with one of these droids being spiked by Nepenthé which was laced with nano-droids and attacked patrons using it's knives.