Police charged a man on Tuesday with possessing explosives and preparing a terrorist act after he was injured in a blast in the toilet of a restaurant in Exeter last month.
Muslim convert Nicky Reilly, 22, was the only person injured in the blast in a family restaurant on May 22.
Devon and Cornwall police said they had charged him with "engaging in conduct in preparation for committing acts of terrorism" as well as two explosives charges.
Two other men remain in custody over the blast, they said.
Reilly had been taken to hospital with cuts to his eyes and burns to his face after the explosion in the toilet of the Giraffe restaurant in a central town shopping centre.
Police repeated their request for information from the public about Reilly.
"Although one man has now been charged, this remains a complex, live investigation," a police statement quoted the senior investigating officer, a detective superintendent whose name was not given, as saying.
"We are therefore keen to speak with anyone who may have information about the man arrested at the scene of the explosion on 22 May - 22-year-old Nicky Reilly - or others they believe may be involved in any capacity.
"Information from the public regarding Mr Reilly's activities, people that he knows or socialised with, what he does and where he goes will all help us build up a picture of Mr Reilly's lifestyle and will assist the ongoing investigation."
