Herbie Hancock has tried most everything, musically speaking. The 67-year-old jazz keyboard legend, who plays Saturday at Berklee Performance Center, has been in on every new leap in jazz, both acoustic and electric.

Start with his early '60s solo work, which included writing "Watermelon Man," which Mongo Santamaria turned into a huge pop hit. Then came his mid-to-late-'60s stint with Miles Davis' legendary quartet, followed by his own groundbreaking '70s jazz/funk album, "Head Hunters." In the '80s, he was a world fusion experimenter and a forward-looking electro-funkster responsible for the highly influential hit "Rockit." In the '90s, he returned to his acoustic piano roots, but that wasn't all. In the past decade, the restless Hancock has been playing with words.

It began with his 1998 dip into the Gershwin catalog on the Grammy-winning "Gershwin's World." In 2005, he turned to pop on "Possibilities," which included collaborations with everyone from Christina Aguilera, John Mayer and Joss Stone to Paul Simon, Santana and Sting.

His latest project is an in-depth study of a kindred creative soul: Joni Mitchell.

"Joni's like a hero to me," Hancock said from his Los Angeles home. "I have a tremendous amount of respect for her, professionally and otherwise. She's a genuine Renaissance woman, a songwriter, a musician, a painter, a poet, and she's sung the gamut. People don't realize, but she's an incredible jazz singer. And yet she defies labeling."

On Sept. 25, Verve will release "River: The Joni Letters," the latest chapter in Hancock's musical journey. He insists it's the first time he's put song lyrics in the driver's seat.

"I'd begun to understand the importance of words in music," he said, "but this was the first time I really let them be the foundation."

Even though he and Mitchell have been acquainted since 1979, Hancock needed help getting a firmer grasp on the correlation between her words and music. He enlisted the assistance of her longtime musical partner and ex-husband, Larry Klein.

"I couldn't have asked for a better collaborator," Hancock said. "We started talking about Joni's metaphors and story lines before we recorded anything. Larry relayed recollections to help clarify things, and occasionally he'd call Joni to clear something up. We went so far as to bring copies of the lyrics to each band member and discuss meanings with them prior to each recording session."

Hancock's diligence paid off. "River" is not only compelling on its own terms, it honors Mitchell's songbook with extraordinary textures supplied by a crack session band featuring saxophonist Wayne Shorter and bassist Dave Holland.

Equally important are the vocalists: Norah Jones, Tina Turner, Luciana Souza, Leonard Cohen and Corinne Bailey Rae, who preserve the intimacy and honesty that define Mitchell's writing career.

In short, Hancock has delivered the best jazz album Mitchell never made - although she does make an appearance.

"We challenged Joni to write and sing lyrics for 'Nefertiti,' but she didn't have time to write something new," he said. "So Larry suggested 'The Tea Leaf Prophecy' " - a biographical song about her parents, especially apt since her mother recently passed away.

Hancock says material from the Mitchell CD will be incorporated into his current tour as rehearsal time allows. But a full-fledged "River" tour is in the offing.

"We intend to take this material on the road," he said. "It'd be silly not to. The preliminary response to the CD has been overwhelming. People already tell me they think it's an important recording."

Herbie Hancock, tomorrow at Berklee Performance Center. Tickets: $50-$75; 617-747-2261.

Towering Hancock: Herbie Hancock comes to Berklee Saturday.