The software - called Tambor - allows publishers to insert an audio advert, using a web interface, into a podcast without the need to re-edit the entire piece.
The software, developed by Tangozebra, is designed to quicken and simplify the process of changing audio adverts and maintain revenue income from older, yet popular podcasts where the original advert is no longer relevant.
The Guardian became interested after previously running campaigns on specific podcasts. In the past it has carried, among others, Renault Megane adverts in a series of travel-focused downloads.
Neil McIntosh, assistant editor of Guardian Unlimited, said:
"This means we can dynamically insert adverts in the studio in the same way as we would insert clips and spikes.
"It means that we can insert ads on the fly. We don't have to go back to old podcasts and edit in a new advert.
"It makes us more flexible and allows advertisers to put new ads into older podcasts."
If the trial is successful, the software could be up and running by the end of September.
A second leading online news publisher is also believed to be using the technology and is expected to make the software live on its podcasts in the next two weeks.
Martin Pavey, Tangozebra's director of advertising solutions, told Journalism.co.uk: "What we have done is to allow publishers, such as the Guardian, to insert piece of advertising into podcasts as they are downloaded.
"This is something very different to the day to day of our online advertising work, but it is very interesting.
"Publishers have to monetise this stuff somehow. I think advertisers will be very interested because there is room for very specific adverts dependent on the subject of the download."
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