The singer has been working on the follow-up to his 2010/11 debut Doo-Wops & Hooligans throughout 2012 and will make a formal announcement in October about the project.
Asked by a fan when they can expect news surrounding album number two, Mars tweeted: "You'll hear something in October. I promise. :)"
Meanwhile, US producer Diplo recently described Mars's new material as "genius pop music" after working with the star for his own album.
"Bruno is the coolest guy I've ever hung out in a studio with," Diplo said. "He's so funny and he doesn't give a s**t. His next album is going to be the biggest thing on the planet. It's genius pop music."
Bruno Mars's debut album Doo-Wops & Hooligans reached number three on the US Billboard 200 chart and number one in the UK.
Watch the music video for Bruno Mars's 'The Lazy Song' below: