Two 20-yeard-old men have been charged over a series of disturbing incidents at fast-food stores in Redcliffe and Southern River last month.
Armadale Detectives say the incidents happened between two stores on four separate occasions.
A man with his face covered sprayed a noxious substance at staff and in the food preparation areas. He is also accused of filming himself during the acts.
Police carried out search warrants at homes in Southern River and Rivervale on May 2 and 3. Officers said they seized items linked to the attacks, including electronic devices.
These allegedly contained videos of the incidents and messages between the two men planning further attacks.
A 20-year-old man from Rivervale has been charged with 10 offences. They include two counts of aggravated burglary and seven counts of causing poison to be administered. He faced Perth Magistrates Court on May 4.
The second man, from Southern River, was charged with 13 offences. They include four counts of aggravated burglary and nine count s of causing poison to be administered.
He was due to appear in court on May 14.
Detectives say both men were allegedly planning more attacks at other locations.
