The 'Wide Awake' hitmaker and the 'Stay' singer - who briefly fell out last October when Rihanna rekindled her romance with Chris Brown - have vacationed together several times in the past but are looking to do something more adventurous this time round, deciding on a getaway to the African wilderness.
A source told The Sun newspaper: ''Kate and Rihanna have both done the Hawaii and Cabo-type trips to Mexico before, so this time they're thinking something a bit different, like a safari in Africa.
''They want somewhere where they can have amazing experiences but still get drunk.''
The pair last took a beak together when Rihanna, 24, whisked Katy, 28, off for a ''girlie'' break to Mexico last year following her divorce from comedian Russell Brand in December 2011, who she had been married to for 14 months.
A source said at the time: ''Katy called Rihanna as soon as she heard Russell was filing for divorce.
''Katy was embarrassed about calling her parents as they'd been so against Russell in the first place, but Rihanna was a great support for her and she really helped to calm her down.''
Back in 2009 the friends jetted out to Barbados shortly after Chris, 23, was convicted of assaulting his girlfriend in February 2009, which he is still on probation for.