BBC South East has revealed Medway Maritime Hospital, in Gillingham, treated 855 patients in corridors in June.
Board papers said it was "the lowest number this year".
The Medway NHS report said all patients treated in the corridor "met acceptable clinical criteria", following snapshot audits through the day and night.
Andrew Stradling, clinical director of Medway's emergency department, said staff talked to patients before they were treated in corridors.
He said: "We talk to them before we put them in any overflow area, so they understand why they're in that area and the fact that it is safe.
"The numbers - the figures of 800 to 900 in a month - that sounds like a huge figure, but that includes everyone even if they just spend 10 or 15 minutes in that area."
He said: "We're very clear that we capture those numbers so we know exactly how bad the situation is."
The hospital has been in special measures for three years.
Kelly Tolhurst, Conservative MP for Rochester and Strood, said: "We know Medway has improved slightly. More people are being seen within four hours.
"While there's no excuse for people to be treated in the corridors, actually that process is being managed by the Medway hospital in a way to try and protect patient safety."
She said: "It's not acceptable long term. But that's one of the reasons why they put in the proposal for the redevelopment of the A&E department."
She said the Â£20m redevelopment would see 11 beds increase to 41 beds - one of which will be used to cope with extra demand.
Analysis by Mark Norman, BBC South East health correspondent
Is Medway the only hospital to treat patients in corridors? Of course not. Sometimes it's called a "cohort" area or an "overflow" area.
All hospital A&E departments are seeing a steady increase in the number of patients they see.
No-one has an answer as to how hospitals deal with the increase.
At Medway, they hope the Â£20m improvements will ease the situation. But that will take time to come on stream.
Meanwhile some patients will continue to find themselves being cared for and treated in corridors and overflow areas.
As many as 12,000 people a year are being treated in the corridors of a Kent A&E unit, figures have shown.