No further action will be taken against two girls arrested on suspicion of possessing a prohibited weapon following an alleged chemical attack at Beaverwood School, Chislehurst.
The two girls, aged 13 and 14, were arrested and bailed after the incident on March 11, which left one girl requiring hospital treatment.
At the time the girl's mother, Kerry Finch, 30, of Mottingham Road, slated the school's handling of the situation.
She said the school failed to inform her about the incident until hours after it had happened and failed to take her daughter, Paris, to hospital.
Meanwhile, the school confirmed it is changing its name to Chislehurst School for Girls last month.