Lavigne shared photos in the studio with the Nickelback rocker to her Instagram on Sunday.
It appears the pair still plans to collaborate, despite announcing their separation in early September.
“YeeHaw! Writing with Chad today,” Lavigne, 31, captioned a photo of herself strumming a guitar in a cowboy hat.
In a second image, Kroeger, 40, smiled as he held tight to his own guitar.
“Back where it all started …” Lavigne said.
The duo previously collaborated on the pop star’s 2013 single “Let Me Go.” The track features vocals from both the stars, and was co-written by the former couple.
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“Through not only the marriage, but the music as well, we’ve created many unforgettable moments,” Lavigne wrote on Instagram at the time of their split. “We are still, and forever will be, the best of friends, and will always care deeply for each other. To all our family, friends and fans, thank you sincerely for the support.”