The owners of iconic St Kilda beach restaurant Donovans have vowed to reopen quickly after a fire took out the kitchen on Sunday night.

Sitting at an alcove table in the restaurant and surveying the damage on Monday, Kevin Donovan told radio station 3AW that the kitchen was destroyed.

He said the dining room was largely intact, although the floor would need repairs. The damage has been estimated at $400,000.

"Gail's [co-owner and wife Gail Donovan] knick-knacks are all sitting here as if nothing happened," Mr Donovan said.

He said one of the dining room staff first noticed flames coming from a canopy and fans in the roof.

"The kitchen staff didn't realise, they were in the kitchen cooking and within minutes the smoke started pouring into the kitchen," Mr Donovan said.

About 55 diners and 20 staff were evacuated to the beach, Mr Donovan said, and it took about an hour to bring the blaze under control.

He said when he and his wife arrived after a phone call two fire trucks were dousing the flames and more arrived later.

"The wind was blowing from the north. We couldn't do anything. We were just standing there watching the flames lick out of the roof," he said.

Mr Donovan said a number of special private events were planned for this week and the restaurant would have to use "tact" when finding a location for those events.

"There are several events, and in the private dining room, that we will have to be sensitive to relocate," he said.

He said the site was without power and phones and the restaurant would set up a temporary office.

Mr Donovan said he was also looking at using mobile kitchen facilities to it to reopen quickly.

"Gail is talking about a sausage sizzle on the beach," he said.

Neighbouring restaurant the Stokehouse burned down in January.