The number of arson cases in Oxfordshire has dropped by over a quarter, latest figures show.
The fall from 474 in 2009 to 345 in 2010 was put down to better cooperation between police and fire services.
Stuart Garner from Oxfordshire Fire and Rescue Service said close communication had proved to be a success.
"We're working in conjunction with Thames Valley Police to put as much effort as we can into reducing the number of fires," he said.
Mr Garner said firefighters were very often the first emergency crews on the scene and so they were being trained to spot evidence of criminal activity.
Unusual or tell-tale signs were then immediately reported to the police so the fire could be properly treated as a crime scene.
All arson cases are then profiled and recorded in a mapping system.
Mr Garner said councils were also involved to reduce the number of potential targets on the streets, like full refuse bins and abandoned cars.
The most recent figures are higher than in 2008 and in 2007 , but Thames Valley Police spokesman said there was now better recording.