Simmons extended the offer to Frehley in a tweet making the guitarist's 71st birthday earlier this week, posting the message, "Happy Birthday Ace. And many more… The invitations still stand. Jump up on stage with us for encores. The fans would love it."
The invitation is the latest in a series of will-they-won't-they communications between the pair, who hooked up in 2017 to write two song's for Frehley's Spaceman album, Without You I'm Nothing and Your Wish Is My Command.
Later the same year, Simmons and Frehley reunited onstage at a benefit concert to support victims of Hurricane Harvey, when they played Kiss classics Parasite, Cold Gin and Shock Me.
More recently, things have been a little more testy, after Simmons told Guitar World that Frehley could return to the band, but only to make guest appearances.
"Ace and Peter Criss have gotten three chances," said Simmons. "They were in and out of the band – fired – three times. For drugs, alcohol, bad behaviour, being unprofessional. So the only reason Ace and Peter were let go the first time, and then the second time and then the third time, is that they weren’t carrying their load."
He added: “Would we welcome Ace or Peter to jump up onstage for a song or two? Of course. Could we depend on either Ace or Peter to do a full set night after night? Not on your fucking life.”
Simmons' remarks sparked a furious response from Frehley, who lashed out at the bassist, calling him an “asshole and a sex addict” in a now-deleted Facebook post.
“Your slanderous remarks about my bad habits over the years has cost me millions of dollars and now that I’m over 12-years sober you're still saying I can’t be trusted to play a whole night’s show!," proclaimed Frehley. “Well that’s exactly what I’ve been doing for the last 12-years with different configurations of The Ace Frehley Band to you and Paul’s dismay!"
Kiss's End Of The Road World Tour is currently in South America, and returns to the US next month. Tickets are available via the Kiss website (opens in new tab). The next title is Kiss's official bootleg series, Off The Soundboard: Live At Donington 1996, will be released on June 10.