Kulick's estranged younger brother Bruce Kulick confirmed the news via Facebook.
"I am heartbroken to have to share the news of the passing of my brother Bob Kulick," Bruce wrote. "His love of music, and his talent as a musician and producer should always be celebrated. I know his is at peace now, with my parents, playing his guitar as loud as possible. Please respect the Kulick family's privacy during this very sad time."
Bob auditioned for Kiss in 1972 and missed out on the gig to Ace Frehley.
Subsequently, he made a career as a studio musician, contributing lead guitars to Reed's Coney Island Baby, among many others albums and tours by the likes of Meat Loaf, Michael Bolton, W.A.S.P. and Diana Ross.
When Kiss's relationship with Frehley began to sour in the late-'70s, Bob was recruited to record guitars in secret for Kiss's Alive II. He went on to become a frequent collaborator with the band, earning performance and songwriting credits on four more Kiss albums, including Unmasked, Killers, Creatures of the Night and Paul Stanley's 1978 solo album.
Bruce became a full-time member of Kiss in 1984 and held the position for 10 years.
The Kulick brothers celebrated their mutual contributions to the band in 2017 with a live show aboard the inaugural Kiss Kruise. Plans to do the same a year later deteriorated, however, amid a falling out between the brothers.
Bruce said in an interview in April that his brother was "not healthy," but he did not elaborate on what was ailing Bob.
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